Update rietveld to r681.
Update rietveld to r681.

Remove django since it's not necessary anymore, rietveld now uses django 1.2 and
it's included in GAE SDK.

Review URL: http://codereview.chromium.org/6749025

git-svn-id: bd64dd6fa6f3f0ed0c0666d1018379882b742947@79521 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

svn2github/chromium-depot-tools,svn2github/chromium-depot-tools,svn2github/chromium-depot-tools