Refactoring: Long option names in push and merge scripts.

This CL is split off from https://codereview.chromium.org/173983002/

R=ulan@chromium.org

Review URL: https://codereview.chromium.org/180873010

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@19632 ce2b1a6d-e550-0410-aec6-3dcde31c8c00