LAPPS-72 created list with status codes
LAPPS-73 Adjusted tests to not rely on dummy data anymore
extended user ressource test class a bit
addded the http status codes constants to user ressource
Completed status codes & swagger api for user ressource
Merge pull request #55 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