Update busboy to v0.2.3
Only load posts once on navigating to content tab

No Issue
- Loading posts from the API should not be necessary in PostsIndexRoute
  because its parent resource (PostsRoute) pre-loads the store.
  Changing the store.find to store.all gets rid of a duplicate
  network request to load all posts.
Correct markup for the PSM author dropdown
Implements User Role Label

Closes #3287.
Add edit roles

refs #3087
- added ability to edit user/roles relation
- user is not allowed assign roles to himself
- only one role per user is supported atm
- added tests
Trim version number in RSS feeds
Merge pull request #3353 from IanMitchell/master

Implements User Role Label
Merge pull request #3355 from JohnONolan/trim

Trim version number in RSS feeds
Hide Settings Tab if Author

Implements #3293. Currently, we don’t have a permission system on the
client side, so this relies on a hardcoded “author” string.
Merge pull request #3347 from jaswilli/posts-content

Only load posts once on navigating to content tab
Merge pull request #3356 from IanMitchell/header-role

Hide Settings Tab if Author
Merge pull request #3343 from sebgie/issue#3087

Add edit roles
Merge pull request #3341 from PaulAdamDavis/psm-class-ammend

Correct markup for the PSM author dropdown
Update Users API to handle role objects or ids

Closes #3357
- API method User#edit now handles User objects that have either
  an array of Role ids or objects.
- Fixed error handler notification on upload modal controller.
Merge pull request #3360 from jaswilli/issue-3357

Update Users API to handle role objects or ids
Hide Settings Sidebar Based on Role

Implements #3294. Currently, we don’t have a permission system on the
client side, so this relies on a hardcoded “author” string.
Merge pull request #3361 from simplabs/update-ember

Updated Ember to 1.6.1
Upgrading Casper to potential 1.0 version
Make user list images background-image's

References https://github.com/TryGhost/Ghost-UI/issues/76

- Swap user avatars in the user list from ing tags to background images
updating tests to match casper