disabled zoom during brushing
zoom changes

Conflicts:
	src/coordinate-grid-chart.js
further experimentation with zoom implementation
wrapped x restriction loop in conditional to prevent error when x restriction is empty
added some pending tests
renamed x domain restrictions to x domain constraints
moved zoom-related tests to jasmine
overhauled zoom-related behaviors to fix issues documented at https://github.com/NickQiZhu/dc.js/wiki/Zoom-Behaviors-Combined-with-Brush-and-Range-Chart
removed render logging
fixed issues with order of render operations