start Session
Starts tracking a new session. You should disable automatic session tracking via setAutoTrackSessions if you call this method.
You should call this at the appropriate time in your application when you wish to start a session. Any subsequent errors which occur in your application will still be reported to Bugsnag but will not count towards your application's stability score. This will start a new session even if there is already an existing session; you should call resumeSession if you only want to start a session when one doesn't already exist.