Merge pull request #55 from learning-layers/rest_api

Rest api
Merge pull request #56 from learning-layers/rest_api

Rest api
Merge pull request #57 from learning-layers/rest_api

Rest api
LAPPS-30
- fixed a bug causing persisting of a comment twice
- modified AppFacadeTest to delete only the data created by it
- modified AppsAndUsersTest to create dummy apps with artifacts,
details, comments and dummy users
Merge pull request #58 from learning-layers/user_domain_model

LAPPS-30