Move bower assets to assets/vendor so we can properly version the zeroclipboard swf

A follow up to https://github.com/github/choosealicense.com/pull/190, this does a few things here:

* Move bower assets to `/assets/vendor` because we can't version zeroclipboard's SWF otherwise
* Move js, css, and img to /assets for consistency
* Degrade jQuery to 1.11.0 for IE backward compatibility
* Version CSS dependencies previously missed

The downside of this approach is that we can no longer concat the CSS and javascript files, resulting in additional HTTP calls, but this should be considered a temporary fix, trading performance for security in order to get https://github.com/zeroclipboard/zeroclipboard/pull/335 out as quickly as possible.