this fixes #108
Merge remote-tracking branch 'origin/develop' into NotificationAPI
Remove debug print (pull #148)
Fix documentation (pull #148)

I had to separate class NotificationSubject in its own file, to cope
with my basic doc generation.
Move get_notification(s) to AuthenticatedUser (pull #148)
Improve test coverage (pull #148)
Complete doc/apis.rst (pull #148)
Merge branch 'topic/Notifications' into develop