add heatmap graph, and reorg some assets

- Created heatmap visualization and hours_by_weeks time factor
- Added rails-assets source to easily add Bower assets
- Had to add different version of highcharts to support the heatmap chart
- moved asset loading out of application layout. This was to prevent an error with highchats not
being available yet when the heatmap chart displayed
fix bubble chart link
move js libraries to a cdn
Merge pull request #48 from dpaola2/heatmap

add heatmap graph, and reorg some assets