Create getter/setter accessors for Gneisschart properties and refactor setXScales, setYScales, calculateColumnWidths

Begin a refactor towards the style discussed in http://bost.ocks.org/mike/chart/ by making getter/setter accessors for most Gneisschart properties (still some work to be done). 

Significantly refactored setXScales and calculateColumnWidths to perform computation in the function in which it's needed, fix a few bugs, and make the functions much more readable.

Rewrote setYScales to fix numerous bugs in how the left and right y-axii interact (fixes Issue #87) and significantly simplify the logic.

This also includes bug fixes for entries with spaces (already in [pull request]( https://github.com/Quartz/Chartbuilder/pull/84)) and fixes for Firefox already merged into master.