[multibar horizontal] Added 'showBarLabels' feature, which displays the labels right next to the bar.
[multibar horizontal] added showXAxis and showYAxis option to chart.
fixed a few lingering d3.v3 issues
Merge branch 'development' of https://github.com/novus/nvd3 into development

Conflicts:
	nv.d3.js
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
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 ~