* Add structure for lists
* Add list timeline streaming API
* Add list APIs, bind list-account relation to follow relation
* Add API for adding/removing accounts from lists
* Add pagination to lists API
* Add pagination to list accounts API
* Adjust scopes for new APIs
- Creating and modifying lists merely requires "write" scope
- Fetching information about lists merely requires "read" scope
* Add test for wrong user context on list timeline
* Clean up tests
* Move ApiController to Api/BaseController
* API controllers inherit from Api::BaseController
* Add coverage for various error cases in api/base controller
- Increase coverage to exercise all parts of each action
- Move into namespace to share common code
- Misc refactor of each action for smaller methods, simpler code
