addressed issue globaleaks/GlobaLeaks#1007

@vecna @hellais : this is my first commit on an unified GLBackend+GLClient repository. 

thanks to maker.

@hellais can you take care of this?

here some of the current glclient limits (not to be handled now but is my point of view in general):
1) authentication is not really handled in a structured/layered way where each action is controlled by the glclient befor being performed. but all is before performed and then checked for errors (e.g. login redirect appens after a user tries to accesse an authenticated resource and the backed deny the access)
2) the same as 1) will need to be applied for authentication.statuses (here with this commit i'm introducing the first set: enabled, disabled, password_change_needed.