Add a Dockerfile to build a gittip container
Added documentation for using Docker
Merge branch 'master' of https://github.com/gittip/www.gittip.com into dockerfile

* 'master' of https://github.com/gittip/www.gittip.com:
  Modify Vagrantfile to use a custom gittip image.
  Keep manual exchanges out of payday self-check
  Append index to schema.sql; #1417
  Fix incorrect  cd added to .profile in Vagrant provisioning.
  Give devs a little pointer re: branch.sql
  Remove os.environ from error handling test page

Conflicts:
	README.md
Added Docker instructions to the Quick Start section
Fixed link to Docker usage
Merge pull request #2288 from citruspi/dockerfile

Dockerfile