Permission table notes

[fyliu]

The permissions stuff needs more exploration to see if we can use something that's already out there for access control. Someone can do a little browsing for that before doing the coding so we don't reinvent the wheel.

Also, I think we need to add a brigade FK to Permisison table to support users that should have access to projects in a given brigade. I I think Bonnie said that "project sponsors" will have certain access to view what's happening to projects. So I extrapolate that to mean "brigade sponsors" will have read permission to potentially all the projects.

We found out from Bonnie that the intent of the Permission table is different than what I guessed based on how the table is laid out. It needs some documentation to clarify what it's actually intended to do.