Homepage: move css & js around

CSS should be at the top and JS should be at the bottom.
This is best practice since you want the styling rules to be on the page
before the html body content gets inserted.

Since we only use the JS after the html is loaded, we can put all the JS
at the bottom which lets the body render faster.

Also use the minified version of jQuery from cdnjs (saves a lot in size)
Remove unused image
Remove Headroom

Since it doesn't seem to be working.  Chrome says there is a JS error
because the header variable is not defined.
Combine document.ready statements

$(function) is the same as $(document).ready(function).  Its just
shorter.
Remove feed.js

Im pretty sure it isn't being used at all
Remove the "Top" link at the bottom of the page

I think this is unnecessary.  The user can scroll up or hit home.
Remove bigSlide

There is not .menu-link element.  From what I could tell, this library
is for making a side menu that show by pushing the page to the right
(similar to a lot of iOS apps)
Fix indentation

Only indent with spaces.  One level of indentation is 2 spaces.  This is
standard for JS, CSS, Ruby and HTML files
Remove center tag, add text-center class

center tags are not supported in the html5 spec
Redo FAQ

Show/hide the answers
Remove the Q and A line headers
Use CSS to style this section
Merge pull request #38 from ScienceCommons/homepage_cleanup

Homepage cleanup