DebuggingSessionManager should be ApplicationSingleton and not ProjectSingleton

For each project a new DebuggingSessionManager instance is created, which is not the intented functionality. This is because it has @ProjectSingleton annotation but not @ApplicationSingleton.

The problem however is that when you switch to ApplicationSingleton then the RevisionManager is not accessible.

Possibly the reason for the behaviour of issue #1 (closed)