username and email request for lti module

added username and email functionality, so that username and email can be passed to the lti third party app
Can we add more description about what the third party is? If we don't tell students any more than this, there is an implicit assumption of a recommendation or endorsement of the safety of the third party, which I'm not sure all course authors will have done. Therefore, giving the student more information about the tool that we are asking them to trust is going to be important, so that they can make an informed decision.