* Add docker configuration and instructions.

* Update node version to 8.11.1

* Add empty string validation to schema.

* Fix leadind dot on error message. Improve ValidationError constructor.

* Configured logging with winston

* Code clean up and reorganization.

* Add CustomAjvError object

* Implemented isValidTerm custom keyword

* Fix issues found by codacy.

* SUBS-1343 (#11)

* Update heroku app url
* Fixed bug on async keywords validation output.

* SUBS-1346 (#12)

* Change term (ontology term uri) representation from string to object.
* Update README accordingly.