Fixes #100.

This commit will transition the ksonnet CLI away from accepting either a
list of files or an environment (or both). A detailed explanation
follows.

Historically, the ksonnet CLI has had several "environment commands".
These commands (e.g., `apply`, `diff`, `delete`, `show`, etc.) all took
one of the following:

  1. An environment name. For example, `apply us-west/dev` will `apply`
     everything in the `components/` directory to the cluster denoted by
     `us-west/dev`.
  2. A set of files. For example, `apply -f foo.jsonnet -f bar.jsonnet`
     would apply those two specific Jsonnet files to the server
     specified by the current context in $KUBECONFIG.
  3. Both an environment name and a set of files. For example,
     `apply us-west/dev -f foo.jsonnet -f bar.jsonnet` would `apply`
     those two files to the cluster denoted by the `us-west/dev`
     environment.

This "duality" remained in place primarily because it was important for
the ksonnet CLI to maintain functional compatibility (though not strict
CLI-level app compatibility) with the kubecfg tool.

Some time ago the ksonnet CLI was forked from the kubecfg CLI, but it is
only in this commit that we abandon this duality. Specifically, this
commit will _require_ the environment name for all commands. For
example, the form of `apply` will now be:
`apply <env-name> [-f <file>]`.

There are main parts to this:

  1. Refactoring core abstractions that supports this "duality".
     Specifically, removing the `cmd.envSpec` type and several
     functions, such as `cmd.parseEnvCmd`.
  2. Updating the tests to reflect this new directory structure.

Signed-off-by: Jessica Yuen <im.jessicayuen@gmail.com>

Generated component name is optional

Rename 'kubecfg version' to 'ksonnet version'

Signed-off-by: Jessica Yuen <im.jessicayuen@gmail.com>

In general, prototypes have a name param. To reduce duplication, use the component name for the name param if the name parameter is omitted. This will turn :

```
ks prototype use deployed-service guestbook-ui \
--name guestbook-ui \
--image alpinejay/dns-single-redis-guestbook:1.0 \
--type LoadBalancer
```

into

```
ks prototype use deployed-service guestbook-ui \
--image alpinejay/dns-single-redis-guestbook:1.0 \
--type LoadBalancer
```

as the `--name` parameter will be inferred. If the operator wishes the name to be different, they can supply the name parameter:

```
ks prototype use deployed-service guestbook-ui \
--name fancy-stuff \
--image alpinejay/dns-single-redis-guestbook:1.0 \
--type LoadBalancer
```

Signed-off-by: bryanl <bryanliles@gmail.com>

Signed-off-by: bryanl <bryanliles@gmail.com>

Initialize namespace to 'default' if not specified

 Clarify errors for commands requiring subcommands

pkg install: Use 'master' as refSpec where version isn't provided

If the namespace is not provided in the target kubeconfig context, use
'default'.

Also squashes a bug where the namespace, server flags may have been
ignored during init.

Signed-off-by: Jessica Yuen <im.jessicayuen@gmail.com>

Currently, if a version is not provided to the following `pkg install`
command

`../ks pkg install incubator/redis`

, the following error will occur:

`ERROR GET
https://api.github.com/repos/ksonnet/parts/commits/incubator/redis

: 404
Not Found []`

This commit will pull in the latest package from master where the
version is not specified.

Also set the default repository ref to 'master' instead of 'test-reg'.

Signed-off-by: Jessica Yuen <im.jessicayuen@gmail.com>

Better support for jsonnet param schemas

Use relative paths on jsonnet imports

Currently, commands such as `ks env non-existent-subcommand` will output
an error `Command 'env' requires a subcommand`.

This is not helpful since the user may assume there is the subcommand
'non-existent-subcommand'. This commit will clarify the error messages
in this scenario.

Signed-off-by: Jessica Yuen <im.jessicayuen@gmail.com>

Signed-off-by: Jessica Yuen <im.jessicayuen@gmail.com>

Signed-off-by: Jessica Yuen <im.jessicayuen@gmail.com>

Currently the schema for the component/params.libsonnet file do not
support top-of-file imports. This change will allow support.

Signed-off-by: Jessica Yuen <im.jessicayuen@gmail.com>

Currently absolute paths are being used for jsonnet imports. This makes
it difficult to share the files across different systems.

Signed-off-by: Jessica Yuen <im.jessicayuen@gmail.com>

Update ks show docs and tweak readme

Signed-off-by: Jessica Yao <jessica@heptio.com>

Signed-off-by: Jessica Yao <jessica@heptio.com>

Signed-off-by: Jessica Yao <jessica@heptio.com>

Document brew install

Signed-off-by: Joe Beda <joe.github@bedafamily.com>

Fix segfault for ks diff

Improve ks init help message

Output usage and return when no command args are provided for `ks diff`.

[docs][prototypes] Rename 'deployment-exposed-with-service' and address README feedback

Improve logging for init

- Add message:  Creating a new app 'foo' at path '/path/to/foo'
- On success, add message:  ksonnet app successfully created! Next, try
  creating a component with `ks generate`
- On failure, provide suggestions for the user.
- Make note that the context is retrieved from the kubeconfig file at
  the environment variable $KUBECONFIG

Specifically,

1. Place more emphasize on project initialization based on context
2. Place ksonnet-lib details into footer.
3. Order examples based on most common use cases.
4. Suggest to visit ks generate

Rename <env>.jsonnet file to main.jsonnet

Fix `nil` dereference error in #129

In line 161 of `root.go`, we're failing to check whether a cluster in
the $KUBECONFIG clusters array exists before using it. This will cause a
`nil` dereference error.

Transition system templates to beta.3

Currently, there are limitations around the file system we are using
that does not easily allow renaming of `us-west/prod` to `us-west`, or
vice versa - `us-west` to `us-west/prod`.

This commit will handle the logic to allow for that by moving the file
contents.

Remove command update