Updating npm post-publish steps

Doing a file-by-file reversion was not working for files housed in submodules (e.g. external/shared).  I changed the work flow to just do a hard reset of the main repo and all submodules.

Be careful when running postpublish.js now!  You could lose staged changes in your repo.

NB: I don't think we need to do a patch for this, as it's just maintenance script functionality.  It can just find its way into the next patch we do.