Course code enrollment page UI

[dwang3851]

On the course code enrollment page, some students did not realize they needed to enter a nickname at this page and save changes to confirm enrollment. As a result, they would leave the page and not be added to the class. We can change the button to say "confirm enrollment" or something similar.

[20wildmanj]

Note: should remove this barrier to enrollment unless they are submitting to an autograded assessment, at which point they should be prompted to fill in, or something similar. Basically, don't have the nickname be a requirement at initial enrollment point.