Find non-proprietary replacements for SWF assets

[dnrce]

Tracks currently uses Open Flash Chart. Would be nice to remove the Flash dependency and instead use something like:

• D3.js (no native pie chart, maybe use NVD3?)
• C3.js
• Chart.js (no combined bar/line)
• jqPlot (somewhat stale)
• Flot
• CanvasJS (kind of ugly)
• Chartkick (native Ruby support but depends on third parties)
• PykCharts (immature)
• gRaphaël

Comparison shopping: http://www.jsgraphs.com/

[dnrce]

Duplicate of TracksApp#1153