Improved MonitoringClient handling

Three changes:

-Added code comments to initial instantiation of Apigee.MonitoringClient

-Pre-populate orgName and appName fields with the value of orgName and appName vars

-Auto-update MonitoringClient whenever value of appName or orgName field changes. This includes:

    -Setting max.orgName and max.appName

    -Re-download apigeeMobileConfig with downloadConfig() so that 'Log a Message' feature works properly

    -Re-start session with startSession() so that session data is captured for the right org/app.