Ensure local served website is properly rendered with css

Commit 9b387e9 updated the layout to have a single `_template.html`, the
issue is that because the base url to serve page on github page and
locally with dexy are different (`github.com/scipy-tutorial-2014/`
vs `localhost/`) having absolute url encoded in the template doesn't work
any more to accommodate both.

This commit simulate the github layout by moving the content of
output-site directory under a folder named scipy-tutorial-2014

Closes #6
Merge branch '6-fix-styling-for-dexy-serve'

* 6-fix-styling-for-dexy-serve:
  Ensure local served website is properly rendered with css