Adding application plans for 'free' and 'paid' based on v2 org billing_enabled

 - adding method to get organizations billing enabled status

 - adding method to get available application plans

 - adding parameter to set application plan when creating app

 - adding method to update application plan

 - updating v2 tests to reflect new service versions and plans

Change-Id: Iaa3bd62037681a0f5fd0c88be4a3b96e1f9f59fc