Merge pull request #89 from Stavrakakis/master

ICS-46 : Post aggregation reintroduced and general Grouping refactor
Chart widths responding to window resize.
Moved window resize event subscription to Chart init function.
Resizing chart width taking margin into account.
Removed console.log debugging.
Tidied Chart constructor and using container offsetLeft instead of chartSVG offestLeft when calculating chart width on window resize
Fixed bug where x position of markers is not correct after resizing the chart's width.
Merge pull request #90 from niksoper/master

Resizing chart width with window.
using naming conventions in Dimension.  ChartGroup now working as event handler
fixed bug in Utils.keySelector that didn't respect a custom keyfunction. Added tests to ChartGroup
Dimension now creates filter functions, ChartGroup has more unit tests, as does dimension
Charts can be drawn without being inside a ChartGroup. Charts are drawn without init now; no need for a redraw() any more.
pre review comments and updates
updated readme example
fixing broken tests post rebase, and a sneaky BubbleSeries bug
updating how scatter series matches d3 data by specifying keyFunction