added custom ordering to Axis, which incudes this in its request for series data
bugs introduced by refactor to bubbleseries fixed
adding getter/setter for post aggregation function
Grouping.getData now checks its own orderingFunction if none is provided by the caller
merge commit to bring in Nick's d3-tip comment update
add a unit test for the post aggregation functionality
removed unused variables
removed jsdoc from private methods inside Grouping
update to parameter names and use of logical and.
Merge pull request #89 from Stavrakakis/master

ICS-46 : Post aggregation reintroduced and general Grouping refactor