Migrate from codekit to gulp

[mattstratton]

Expected behavior

Anyone should be able to develop on the theme without requiring the commercial software CodeKit.

Actual behavior

You need CodeKit right now because @mattstratton uses it.

The idea will be to add some gulp tasks, and probably some watch stuff (maybe replacing the hugo watch things, possibly?) for when working on local theme development.

NOTE: this does NOT affect any content type stuff for users in devopsdays-web.

[mattstratton]

The main thing that seems challenging is that I am using a feature of CodeKit to concatanate the javascript files, using a proprietary syntax. I think it should still be do-able though.

[mattstratton]

I'm going to re-open this, because while I may have created some gulp tasks, it's not documented.

This is also tied to #632 as the bower dependency exists because of codekit.

[bridgetkromhout]

Should this be a "write documentation" task?