FR: Award / Penalize user functionality

[AtomicMaya]

Is your feature request related to a problem? Please describe.
A good idea would be the ability to award users points in the case of "proof of work" challenges or to penalize them if they have been caught cheating.

Describe the solution you'd like
On the member page, or the team page (if the "force team" option is activated) a button should exist that says "Award User".

Clicking it opens up a modal (like the hints box) that asks for "Reason" and "Points" (which can be a negative value to penalize a user). That award/penalization should end up in the score calculation.

Describe alternatives you've considered
Current solution included making a one-time challenge and giving the flag directly to the person. but this would not work if it were a penalization (as mentioned in #200 )

[0xAda]

This is already implemented, https://github.com/ractf/core/blob/master/src/challenge/views.py#L164-L215 but is currently lacking frontend support. It might be nice though to have some sort of functionality that optionally exposes these extra scores to the user, along with the reason they're there.