simple hack to get elastic to work with binned groups

i don't claim this is correct or general, just want to keep the conversation
moving

Conflicts:
	dc.min.js
Merge pull request #319 from dottedmag/master
Tooltip elements should be drawn on top of chart paths
Merge pull request #321 from sclevine/master

Tooltip elements should be drawn on top of chart paths
remove unneeded semicolon
Fix graphical glitches in charts due to stale data
Merge remote-tracking branch 'origin/pr/322'
add link to api docs
Add docs for Capped
fix nested function jshint issue
factor out mandatory attribute check
build artifacts
first pass of a heatmap
Add BoxPlot
add semi-colon
add heatmap onClick handlers
Rename local variables in `group.stack` method
Added support for hiding and showing individual graph stacks
Added documentation for chart stack hiding/showing for grunt docs
Merge pull request #325 from sclevine/master

Added support for hiding and showing individual graph stacks