tests for composite chart when one crossfilter group is shared between 2+ sub charts

add sharing title options for composite chart

legend names bug fix. updated groupName chart storage index
Merge pull request #373
Merge pull request #357

Conflicts:
	test/legend-test.js
fix lint
Added BarChart legend tests, and reorganized legend tests
Moved legend tests for individual charts into chart tests
Merge branch 'barchart-legend' into testing
Updated coverage report for legend test updates