User management with tests, no session logic yet.
Merge branch 'develop' of https://github.com/IgorLeshchenko/hb-app into develop

Conflicts:
	server/src/main/java/org/lessi/chb/usermgmt/InvalidCredentialsException.java
	server/src/main/java/org/lessi/chb/usermgmt/User.java
	server/src/main/java/org/lessi/chb/usermgmt/UserManager.java
	server/src/main/java/org/lessi/chb/usermgmt/UserRegistrationHandler.java
Response sending corrected.