group chat tables now use membership as reference

This change was done to leverage the additional course and role
information that is found within the membership table.
group chat session table now tied to a course
Merge remote-tracking branch 'upstream/master'
Merge remote-tracking branch 'upstream/master'
methods to add group chat data

Methods have been added that can be called to initiate a chat
session, add users to it, and add chat messages. In addition,
a user's chat settings can now be saved.
fixed spelling error in group chat settings method
Merge pull request #64 from jjunk/master

group chat tables updates, as well as, creation methods