Allow manual creditation

**Is your feature request related to a problem? Please describe.**
An admin should be able to manually grant some percentage of points for a test to a team. This would enable similar functionality to what is used at CyberStorm where the admins can manually grant partial credit to teams if they choose to.

**Describe the solution you'd like**
Somewhere in the team submission history, you should have a button "Give Credit" which will open a dialog where an admin can specify how much credit to give. This credit should be revocable if the admin realizes this was a mistake.

This will have corresponding server changes.

**Describe alternatives you've considered**
NA

**Additional context**
NA

Start by locating the team submission history and the related server entry points. Define how an admin specifies partial credit, how the credit is displayed, and how an accidental grant can be revoked. Done means the UI and server support granting and revoking credit consistently.

Written by the indexing model from the issue text.