Fixed heatmap leaflet website page.  Added working leaflet 0.8-dev examp...

Leaflet 0.8-dev has a lot of API changes, so I made a new leaflet heatmap example that reflects these changes.  Also fixed a small issue with the original leaflet example.

Since leaflet 0.8 is still under development and not available in a CDN, i had to include the leaflet source.  Can get rid of these later once the library is released and available on their official cdn.