Add push-to-trunk python port.

Preliminary version.

TODO: Add wrapper script in tools dir.
TODO: Some refactoring.

R=jkummerow@chromium.org

Review URL: https://codereview.chromium.org/49653002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@17600 ce2b1a6d-e550-0410-aec6-3dcde31c8c00