Recreate directory structure from pages/ to site/

This way you can organize your .md files in the way you want the .html
files to appear in the final site. At this point, the testing structure
that I was using wasn't able to scale to having more than a couple pages
since I was explicitly checking for the page information.

We're going to need to switch to a more general testing structure now.

closes #4
Merge branch 'master' of github.com:rpicard/gassy