Csharp Device Client

• Renamed Method and Twin samples
• Modified file upload e2e tests to use a single fileNotificationReceiver
• Added four first class properties on Message class
• Upgraded dependency WindowsAzure.ServiceBus to v4.1.2
• Added SetDesiredPropertyUpdateCallbackAsync and obseleted the non async api

Csharp Service Client

• Add four first class properties on Message class