rails 4.1 support (still works in 3.2)
rails 4.1 support (still works in 3.2)

Change-Id: I614a3a6159b998f43cc37c8f44ec6713c9c5d632

LeonidMorozov/lti_provider_engine,LeonidMorozov/lti_provider_engine,instructure/lti_provider_engine