username and email request for lti module

Necessary for MIT course starting early October. Please merge as soon as possible to facilitate feature testing.

added username and email functionality, so that username and email can be passed to the lti third party app
Yes, the current implementation means that if the user does not want their information passed, then they will need to not click the LTI button. There wasn't an easy way to request a data policy from the third party and have that reflected on the edx site. In the end, Lyla said it was fine to have a text box where the course creator would explain how the third party would use the data.