users can comment on problems
Merge pull request #12 from ToreyStapleton/master

users can comment on problems
users can see/delete their own comments
Merge pull request #13 from ToreyStapleton/master

users can see/delete their own comments
can see all problems/notes by a certain user
Merge remote-tracking branch 'upstream/master'
Merge pull request #14 from ToreyStapleton/master

can see all problems/notes by a certain user
Merge branch 'master' into homework