Skip sorting if we don't want to sort.

The JS sort function @line 109 is not stable (order is not necessarily preserved for elements that compare 0) so when order == false and all elements compare 0, save the time and skip the sort call, so the original order is preserved.  

Also it seemed partly wrong for the compare function to return false instead of 0.  If the sort algorithm does false === 0 it may have issues.  This does seem unlikely though.
Improved handling of null values when sorting, absent values for asymmetrical selections, and updated tests
Update version in package.json and bower.json
Add undefined check to sorting
Merge pull request #8 from keenlabs/update/fixed-sorting

Debugged and improved sorting method