Added zero line for discreteBarChart and multiBarHorizontalChart
Merge branch 'development' of https://github.com/novus/nvd3 into development

Conflicts:
	nv.d3.js
	nv.d3.min.js
	src/models/multiBarHorizontalChart.js
build
Removed an inline opacity style in multibarhorizontalchart
Fixed bug in stackedAreaChart where the tooltip highlight lines would not show up for negative stacked charts.
Rebuilt nv.d3.min.js
Fixed non-matching changestate length in linechart
Fixed non-matching changestate length in stacked area chart
build
Merge branch 'development' of https://github.com/novus/nvd3 into development
build
fixed an issue with legend placement
Update nvd3 d3 dependency to ~, so no conflicts with packages who also require d3 at a newer 3.3 version.
Merge pull request #376 from DavidSouther/d3_dependency_update

Update nvd3 d3 dependency to ~
Made a fix to calcApproxTextWidth, to fix bug on IE9.
Merge branch 'master' into development
Added a 'noErrorCheck' method to cumulativeLineChart
ran grunt production to make nv.d3.min.css. Also tagging for version 1.1.15b
updated README
Update bower.json

Bumped to 1.1.15-beta.