addition and subtraction working, sort still broken
fixed ordering bug for multi-dimensions and added tests
Merge branch 'multidim'

Conflicts:
	dist/InsightCharts.js
	dist/InsightCharts.min.js
	doc/DataSet.html
	doc/DataSet.js.html
	doc/Dimension.html
	doc/Dimension.js.html
	doc/Grouping.html
	doc/Grouping.js.html
	doc/InsightCharts.Constants.js.html
	doc/index.html
	doc/module-InsightUtils.html
	src/mda/Grouping.js
	tests/Grouping.spec.js
changes to dimension
Merge branch 'multidim'