This commit updates the sources to be Play 2.3 compatible. Furthermore the whole WebSocket system has been refactored and optimized.

Classes:
- AdminAction: Change SimpleResult to Result as of Play migration guide
- Component: Change SimpleResult to Result (see above), change import of play.api.templates.Html to play.twirl.api.Html
- FriendshipController: Change alreadyFriendly to alreadyFriendlyTransactional
- NotificationController: Remove deprecated imports, Play 2.3 compatible
- PostController: Add transaction to post.create() and parent.update()
- ProfileController: Add transactional methods
- WebSocketController: Implement new WebSocketController for WS refactoring
- NewNotificationActor: Remove class as refactored in WebSocketActor
- WebSocketActor: Implement new WS actor
- IJsonNodeSerializable: Add interface for JSON serializable classes
- NotificationService: Add method webSocketPush to instant push WS message on new notification for online clients
- WebSocketService: Implement WS service to handle WS messages and methods. Also handles open WS client connections
- Account: Improve transactional methods, implement getAsJson()
- Friendship: Improve transactional methods
- GroupAccount: Add findEstablishedTransactional()
- NewNotification: Implement getAsJson()
- Post: Improive transactional methods
- Global: Change SimpleResult to Result

Templates:
- Tiny fixes to be Play 2.3 compatible

JS:
- notification.js: Refactoring in order to fit the optimized WebSocket system, general code improvements

Other:
- applications.sample.conf: Add db.default parameters to avoid problems with DB timeouts
- routes: Add general WS route
- build.properties, plugins.sbt, build.sbt: Change version as of Play 2.3 migration guide