Basic implementation of App missing

A basic implementation of the App needs to be added. Only the skeleton / an empty class is enough.

Requires: Basic implementation of IMiceGUI missing (#44 - closed), Implement: IDataCollector (#21 - closed), Basic implementation of IController missing (#45 - closed), Implement: Response (#2 - closed), Implement: Request (#1 - closed), Basic implementation for the MiceGUIManager mis... (#46 - closed), Basic implementation of DataCollector missing (#36 - closed)