Integrating the new online interface with the application.

* Renamed LoginManager to SessionManager
* Replaced get_mpt27 with get_mpt34
* Removed some of the existing login/logout stuff (TODO: still need to remove other bits of it which are no longer used)
* Removed TutorialInterface._send_data, replaced calls with SessionManager.get/post

A functional change is that when not logged in, instead of "You don't appear to be connected" messages, users get prompted to log in.
Merge branch 'sso' of github.com:CSSE1001/MyPyTutor into sso

# By sapi
# Via sapi
* 'sso' of github.com:CSSE1001/MyPyTutor:
  Changed all decoding to utf8 (from ascii)

Conflicts:
	code/tutorlib/online.py