[#16420705] helper methods for controllers. lazily binds a datastore & push client per request using the appropriate headers. 
[#16420705] helper methods for controllers. lazily binds a datastore & push client per request using the appropriate headers. 

Only works with sandbox keys right now.
jnlopar/stackmob-ruby,johnkchow/stackmob-ruby,sirnicolaz/stackmob-ruby