'Make' commands to tag builds and push to npm, master, and gh-pages, all...

... upstream.

The new targets are really just commands to be executed in order.
'git-update-publish' is the only one we need to issue. This command will only
work if you have write-permission to google/traceur-compiler

Review URL: https://api.github.com/repos/google/traceur-compiler/issues/853

Closes #853.