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.