load_XXXX() methods now return the number of adaptors which have appeared in the registry due to that method's invocation. This can be used to report success or failure to load databases.

Improving the error handling of the DBI connection in load_registry_from_db(). We now report an error if it cannot connect to the MySQL DB and if it was not pingable. Hopefully this catches both erronious scenarios.

warning if species alias is not found.

In get_DBAdaptor(): Thow exception if species alias not found (excactly
as in get_adaptor()).

found in get_adaptor().  Suggested by jm18 on dev.

Also reformat get_alias() and get_DBAdaptor().

than {}.

there's no ontology database available.

report warning if regitry call to get_alias is called with an invalid species name. Also had to add option to get_DBAdaptor to not look up aliases so that warning are not given the first time we use it

do its thing.