Read focusItem in GridLCA

399884: [Grid] getFocusItem always return null
https://bugs.eclipse.org/bugs/show_bug.cgi?id=399884
Implement GridItem#set/getCheckable and GridColumn#set/getCheckable

399885: [GridItem][GridColumn] set/getCheckable is missing
https://bugs.eclipse.org/bugs/show_bug.cgi?id=399885
Preserve/render custom data for GridItem

402521: CustomData will not be rendered for items
https://bugs.eclipse.org/bugs/show_bug.cgi?id=402521
Replace org.json parser with the new simple one.
Adjust to changes in ClientObject in RAP 2.1

Use JsonValue instead of Object
Eliminate the usage of IClientObject#set( Object )
Eliminate the usage of deprecated ClientObject.set( String, Object)
Adjust to changes in RAP: use JsonValue instead of Object
Adjust to JSON-related changes in RAP, code cleanup
Adjust to changes in RAP: use EventLCAUtil.isListening
Get use of org.mockito.mockito-all 1.9.5
Revert "Get use of org.mockito.mockito-all 1.9.5"

This reverts commit 8c972fae4bf993804c0cbbe52dd4c41a5cf88dca.
Use mockito-all
Remove org.eclipse.rap.jettycustomize bundle from launch configs
Initial import of org.eclipse.rap.nebula.widget.grid.demo.examples
Fix typo in bundle name
Update project an manifest file
Change examples demo table data
Remove unnecessary code selection listener
Move demo bundles to 'examples' directory

Rename bundle org.eclipse.rap.nebula.widgets.grid.snippets to
org.eclipse.rap.nebula.widgets.grid.demo.standalone