[People] Display course role as a column of information on the confirmation screen

[gpillsbury]

Problem statement:

When adding a user to a course, the dialog allows you to specify a role for that user. In the confirmation screen, the user's name and pertinent information is displayed to confirm the correct user is being added, but the role chosen for them is missing. The dialog needs to confirm *both* bits of information to avoid accidentally adding someone in an incorrect role. There is no way to know this in the current confirmation dialog.

Proposed solution:

Add "Course Role" as a column of information on the confirmation screen.

User role(s):

admin,instructor