moved advanced tool section from about page to top-level navigation

Hey Team,

I'm currently setting up a virtualbox appliance to be used in health surveys across Africa.  We will be using many of the advanced tools, but had trouble finding them because they were tucked away in the about page.  I have made another top-level section which includes these tools.  I copied the "Advanced Tool" section basically as is, but also made the hrefs relative path (earlier pull request). 

I'm really blown away by what yall have done with fieldpapers.  I have successfully setup it up on ubuntu 14.04.

Thanks for your awesome work,
-Brendan