edx/edx-platform — pull request #2220 by ahmadix (2014-01-17 20:12:57+00:00)
Title: fixing roles parameter in launch data

according to IMS Global
http://www.imsglobal.org/LTI/v1p1p1/ltiIMGv1p1p1.html#_Toc330273026

the launch parameter is `roles` not `role` which result in wrong assumption inside the Tool Provider side when I used it.