Change banner link and index.html copy

Normally when you click the top left header logo, you are brought back to the main website (transit.geotrellis.com), rather than a different one (geotrellis.github.io).

Clarified example question copy.
Change index_new.html navbar links

to transit.geotrellis.com and add new one for the docs site at geotrellis.github.io
Change scenic_new.html navbar links
Update index.html navbar link
Merge pull request #65 from andrewbt/master

Navbar links and copy editing