Group admin ability to delete groups

[sacrevert]

From @andrewvanbreda

I don't think it would be impossible as there is a deleted flag on the database. I did actually query this oddity with John once, and I can't remember exactly, but his answer related to something like it was never added because groups had an expiry date. It shouldn't be hard to do.

[andrewvanbreda]

@sacrevert Fixed and live. Also fixed problem where Edit Project Details was never displayed for administrators.