OSX: Added remote commands to SyncDeviceManagerService. Bug fixes.

- SyncDeviceManagerService:
- Added remote commands for player
- Fixed bug where the album art would be downloaded too often (added
album art key). Also moved album art from PlayerMetadata to SyncDevice.
- Updated UI in SyncWindow (remote commands are working, layout
updates).
- Updated SyncPresenter with remote actions.
iOS: Updated project after changes on other platforms.

- Now making the disctinction between iPhone and iPad in
ISyncDeviceSpecifications.
- Updated SyncViewController.