modified the ShellViewModel so that when it receives a stop message it will stop the playback instead of setting the media source to null
fixed issue with showing the embeded video playback view model in the playback view
moved the MugenServiceLocator to the Client.Common module
added the suspension manager and suspension manager exception classes tit the client assembly
fixed some issues with view's code behind files who were missing the call to InitializeComponent
added leftover files from previous commit
renamed the SubsonicService class's  is configured method to HasValidSubsonicUrl
moved some of the logic regarding settings from ShellViewModel to the App and MainViewModel classes