Feature/change commenting

Change commenting

Add Tapatalk inspired change commenting to the change details viewer so signed in users can add a comment and review changes.

[x] Layouts for quick commenting and advanced commenting
[x] New processor for handling comments and reviews
[x] Fetch and store permitted labels for a project
[x] Retrieve and display these permitted labels and permitted values for the current user
[x] Review hookup and testing
[x] Save comments in cache when leaving advanced commenting view
[x] Load comments from cache when entering advanced commenting view
[x] Only allow signed in users to be able to comment
[x] Show a message when successfully commented and close advanced commenting view (clear message from cache as well)
[x] Fix colour of quick commenting buttons
[x] Hide labels section when there are no labels
[x] Copy message updates from advanced commenting view back to quick commenting
[x] Set default label to previous rating or default value
[x] Keep existing database data for users on the latest version (so they don't have to log back in again)
[ ] Make transition nicer (slide not fade)
Screenshots

Quick commenting: screenshot_2015-11-28-12-01-42

Advanced commenting: screenshot_2015-11-28-12-01-32

refs #11 (Basic commenting (text only) and Advanced Commenting with ratings)