Adding Header For IPython Notebook in Bootstrap 3 Theme

jakevdp had converted Pelican-Octopress theme to use Ipytgib Notebook better and
I wanted to be able to do that. So I modeled my changes on his. Just needed to add some code to the header to incoprorate additional css handling the Notebook.

* Just needed to add three lines to header to later pull in code when Pelican generates code
* see https://github.com/duilio/pelican-octopress-theme where something similar had been done