Canvs-based generation and image export methods

Refactored and added a host of methods for drawing without utilizing SVG, including drawing to a page canvas and creating PNG/JPEG/++ data URIs via dummy canvas. Now image export should be secure and supported in a much wider array of browsers (incl. Safari 5+).
merge pull request #7 from tdhsmith/gh-pages
Cleanup js and move colorbrewer out of global namespace

- Remove canvas implementation (not 1:1 compatible with SVG output)
- Move colorbrewer out of global namespace to Trianglify.colorbrewer
- Trianglify now passes JSHint with no syntax issues!
minor style changes