Closes #186 - Use Grunt plugin to manage theme settings.

Hi guys, here's my implementation of the [grunt-shopify-theme-settings](https://github.com/discolabs/grunt-shopify-theme-settings) Grunt plugin for Bootstrapify. Everything got ported across fairly smoothly, the exceptions being some of the funkier box layouts you were using in your settings HTML got lost. Hopefully the convenience of the YAML syntax is worth it :).

Here a couple of screenshots of the settings panel [before](https://cloud.githubusercontent.com/assets/702485/4360791/113b36c6-427f-11e4-9eb3-23864b57dfab.png) the changes and [after](https://cloud.githubusercontent.com/assets/702485/4360790/1124fa64-427f-11e4-905a-c63b695ea32f.png) the changes, so you can cast your eyes over it.

I also did a double-check that no settings were lost or changed names by doing a diff on the output of `$('#theme_settings_form').serializeArray()` from the Javascript console in Chrome when viewing the  before/after settings.

Let me know what you think, looking forward to any feedback you might have!