Restore "Forks" to Paste

Summary:
I just put them in the property table instead of a list at the foot, they looked weird down there and were too bulky relative to their importance.

This won't scale great if someone forks a paste ten thousand times or whatever, but we can deal with that when we get there.

Also clean up a few things and tweak some styles,

Test Plan: Looked at forked, unforked pastes.

Reviewers: btrahan

Reviewed By: btrahan

CC: aran

Differential Revision: https://secure.phabricator.com/D3295