Fixes #22; Fixed Pie Transitions

This addresses an issue where pie charts were getting "out of sync" with the data model and not removing / repositioning old arcs. The fix was to simple select all and remove before rendering the arcs in the SVG. Unfortunately this does little to address #1 since this approach doesn't allow for smooth transitions. Seems better to ensure it is working correctly now and worry about smooth transitions later.
Fixes #41; Fixed bucketing for the Heat Map

The old implementation used a string based map that would cause issues with certain ranges and numbers of buckets. The new implementation does the following:

* Faster bucketing - uses simple integer math to perform discrete bucketing
* Explicit boundry conditions - Easier to read and ensures out-of-range data is explicitly handled by the routine
* Fixes numerical rendering errors - No longer assuming a string based lookup map allows us to ensure a total order on the prepared buckets.
Closes #32; Significantly Improved QueryCSS

QueryCSS now takes the full DOM tree into account when collecting styles from reference elements. Previously the query was limited to only the containing element of the canvas and completely missed styles that referenced parents further up the DOM tree. Now we build a full tree, up to (but not including) the body tag and use it query styles.
Fixes #46; Removed default black stroke from real-time area plots.
Merge pull request #47 from fastly/rsandor/remove-real-time-area-stroke

Fixes #46; Removed default black stroke from real-time area plots.
Merge pull request #45 from fastly/rsandor/better-query-css

Closes #32; Significantly Improved QueryCSS
Merge pull request #44 from fastly/rsandor/fix-bucketing

Fixes #41; Fixed bucketing for the Heat Map
Merge pull request #40 from fastly/rsandor/fix-pie-transition

Fixes #22; Fixed Pie Transitions
Fixed merge conflicts for the pie chart.