Cleaned up some cruft in the footer. See below:

- added link to /about
- added default email address (currently alan.delevie@gsa.gov)
- commented out Oakland branding
- hardcoded sign in link in footer

Deleted commented out CfA footer, per amoose's request.
Merge pull request #273 from 18F/feature/fix_footer_links

Cleaned up some cruft in the footer. See below: