Merge pull request #16 from tehandyb/master

Treemap and Sankey handle condition where there is no data.
afterZoom bug fix and doc fix for geoChoroplethChart
geoChoroplethChart: stop selection on drag
added negative data message for treemap
negative value goes to zero for bar gauge
fix line thickness on reset zoom button click
added message for sankey that receives all negative values
fixed negative message function
merged Negative Total Capacity Handling with upstream