CYB-367 - Window scroll in Gallery is making it hard to navigate

https://jira.ets.berkeley.edu/jira/browse/CYB-367

This PR does a number of different things:

- Prevent the full gallery list from being reloaded on every page view
- Implement iFrame resizing for all 3 LTI tools
- Implement scroll position caching for the gallery tool
- Improved sorting in engagement index
- Fixed bug in liking/disliking code
- Fixed removed activities bug in Points Configuration (https://jira.ets.berkeley.edu/jira/browse/CYB-212)
- UI code simplification where possible
- Consistently use Services, Factories and Controllers
- Added significant documentation throughout the UI codebase
- Added pointers for possible REST API improvements

As this is my first significant work using Angular, I would appreciate a thorough review that completely picks this apart ;) /cc @christianv @raydavis 
I agree that `$scope` is being misused here. However, using a service doesn't seem entirely right either as the CommentController is just trying to call a function in the ItemController and the controller don't really want to share data and/or code with each other. On top of that, the logic that would be abstracted out really is controller logic.

Therefore, what would you think about sending a `$.broadcast` event from the CommentController and catching it in the ItemController instead?