If student doesn't have a rank, there is no easy way to set without promoting student

[tkeppers]

There are a few (older) entries that don't have a student rank set for whatever reason. We can set the rank by promoting the student to the next level, but there is no easy way via the UI to set the student's rank as WHITE belt.

Possible fixes:

• Open up the UI to allow manual modification of student rank (could cause other problems if we don't limit the input to approved values, would also permit unofficial promotion of student without going through the promotion process)
• Default WHITE if student rank is missing. Probably the easiest and best solution, but could possibly cause issues with higher ranking students if something else is causing the current rank to invalidate.