Ripped off from adrianshort.org
$ git remote -v
origin https://github.com/hakimel/reveal.js.git (fetch)
origin https://github.com/hakimel/reveal.js.git (push)
$ git remote rename origin upstream
$ git remote add origin https://github.com/benschw/new-presentation.git
$ git remote -v
origin https://github.com/benschw/new-presentation.git (fetch)
origin https://github.com/benschw/new-presentation.git (push)
upstream https://github.com/hakimel/reveal.js.git (fetch)
upstream https://github.com/hakimel/reveal.js.git (push)
$ git push -u origin master