Move feed off home page to just /feed/

Summary:
I haven't actually been using this as much as I thought, and am more interested
in the full view than the per-project view.

Let's try moving it off /home/ and then maybe adding some filtering options at
some point.

Test Plan: Looked at "all" and "my projects" in feed. Looked at home page.

Reviewers: btrahan

Reviewed By: btrahan

CC: aran, epriestley

Differential Revision: https://secure.phabricator.com/D1658