Add type attribute to stylesheet link tag
Remove some unused stylesheets

I couldn't find anything using their selectors.  This should be safe to
remove.
Move homepage styles into style.css
Remove unused itemscope attribute
Fix up html errors in the nav

I also added an id to the nav-collapse so that the data-toggle is
guarenteed to target the correct one
Merge pull request #41 from ScienceCommons/more_cleanup

More cleanup