Updating nv.d3.js to newest version. Adding d3.v3.js. Updating index page
to use new nvd3, plus tooltips.
Updating readme with short description of what this repo is for.
Updating line.html example. Adding prettify.js.

Changed line.html to load the example code asynchronously from file.
Removing DISQUS threads from examples.html and line.html
Updating scatter and stackedArea chart examples.

Updated copyright year on all example pages.
Updated discrete bar.
Updated line plus bar chart example.