Require owner email to change semester

[jacksontromero]

Right now, Admins can change semester but this kicks them out and requires the owner email. Admins shouldn't have permissions then.

Longer explanation: Right now there's a hard-coded owner_email that's set as a server environment variable. After changing to a new semester, someone has to log in with the owner email in order to add new TAs to the blank semester. However, Admin TAs have the permissions to change the Semester, even though they won't persist to the new semester. We observed a failure mode where over the summer, Anne (who was an Admin), changed the semester but that locked her out of the queue because she didn't have access to the owner email.

So, two potential solutions are:

• Require the Owner to change semester, remove permissions from Admins
• Automatically copy Admins when making a new semester