Add form for Territory editing

[amaury1093]

Edit the start/end dates and color, and add a hook with the upload feature.

[quorth0n]

I think the backend is pretty much ready for the MVP, so I think I'm going to move over here until then. Feel free to assign me on this if you haven't started already; shouldn't take as long as the last one now that I've gotten the architecture down 😄