Added gh-pages grunt task

@pfiller This is pretty straight forward. It's creating a dist directory and copying in the all the required files for the gh-pages branch. It then run the plugin task and commits the new files up to the gh-pages branch on GitHub. The dist directory is ignored and erased after it pushes.

Note: This is a PR against the version-not-updating-in-comments branch. Let me know if you want this merged into that branch first, then into master or the other way around.