Add Features from cwohlman fork

On [my fork](https://github.com/cwohlman/KoGrid) I've added numerous features to the kogrid:

 - Added grouped rows and aggregation
 - Add a footer row which will show totals for each column
 - Improve the naming of the group column
 - Support for sorting grouped grids
 - Create Expand/Collapse-all buttons
 - Improve speed of grouped grid, esp when expanding and collapsing rows
 - Add an amd module output to the build process
 - Add cell selection and improve row selection

To see the grid in action please see the [example page] (http://cwohlman.github.io/KoGrid/)

I'd like to see these features available to everyone else using the kogrid.