closes#3400
- The user view has been extended to have properties indicating whether
the user has rights to make the displayed user an owner or delete
him/her
- Handlebar conditionals decide whether or not to display the cog
Closes#3402, Closes#3428
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### Components
- Added GhostSelectComponent to handle async select creation (h/t @rwjblue)
- Added GhostRolesSelector (extends GhostSelect) for displaying user role options
- Created StoreInjector for surgically inserting the store into things that normally wouldn't have them.
### Users Settings
- InviteNewUserModal now uses GhostRolesSelector & defaults to Author
- The role dropdown for user settings has permissions set per 3402
### User Model
- Added `role` property as an interface to getting and setting `roles`
- Refactored anything that set `roles` to set `role`
- isAdmin, isAuthor, isOwner and isEditor are all keyed off of `role` now
### Tests
- Added functional tests for Settings.Users
- updated settings.users and settings.users.user screens
- fix spacing on screens
### Server Fixtures
- Fixed owner fixture's roles
closes#3222
- implementing server-side pagination for /users API
- passing /users?limit=none will return all users
- passing /users?status=invited will filter base on user status
- creating 3 mixins (route, controller and view) to keep pagination logic DRY
- updating route, controller and view for Posts to use new mixing
- implementing infinite scrolling for Users Management screen (using new mixins)
- Users Management screen displays all invited users, but paginates active users
