First phase of refactor + dynamic columns
Added the ability for dataGridColumns to update their references if the name attribute has been changed
Added ability for dataGrid to change its column definitions and update with the new templates

Added ability for dataGrid to handle changing the number of columns
Changed deriveItemShape to use the actual item rather than the properites in dataGridColumn
Moved common row-rendering code into single function and refactored dataGridHelper to use new rendering function
Added dynamic columns example
Fixed behavior when columns are removed
Removed batchRender and initialRender attributes and their uses from dataGrid
Added examples to dataGridKitchenSink and fixed action event propagation
Added and cleaned up some comments in dataGridHelper
Fixed dataGrid not generating rowData if items are changed before rendering
Merging origin/jye/master-pending-datagrid-asyncColumns into master