Fix bug where mixen didn't work properly with Backbone.extend.  Fixes #2.
Fix test include
Merge branch 'master' into gh-pages
Update docs
Merge branch 'gh-pages' of github.com:HubSpot/mixen into gh-pages

Conflicts:
	docs/build/intro.html
	docs/build/resources/templates/base.jade
	docs/build/resources/templates/includes/page-header.jade
	index.html