Add image upload to new guides

Getting back into it!

![screenshot 2014-11-25 18 27 03](https://cloud.githubusercontent.com/assets/485583/5182234/03d700e8-74d2-11e4-8ceb-50f9c511623b.png)

# What's changed
* Adding image uploading to creating a new guide - there's some things here that can easily generalized to other upload processes as well (ex: fa-spin uploader)

# What's next
* The next stage of the new guides pages.