Fixed a problem from a previous commit.

Somehow one of the classes I added was removed from the include list,
so the app was crashing when you tried to load the meeting page. Fixed
it now.
Changed the tab bar color to FORCE-Green.
Added a .gitignore file so we don't keep commiting changes to files that don't need to be tracked.

I used the github default file
(https://github.com/github/gitignore/blob/master/Objective-C.gitignore).
 Since we have already commited or own file, it will continue to be
tracked. You can remove it from the repository (but keep it on your
system) by running the following command, but replacing 'nathan' with
your username.

git rm --cached
app/FORCE.xcodeproj/project.xcworkspace/xcuserdata/nathan.xcuserdatad/Us
erInterfaceState.xcuserstate