[FIX] Databinding: Update asynchronously on twoway property changes

This fixes the generic databinding issue with editable controls in
lists, where changing the editable control does invalidate the list and
causes update of the aggregation. As this happens synchronously, the
control where the change is originating from is destroyed, while the
change handler is still processed.

- Added async flag to setProperty method of models
- Added async flag to checkUpdate method
- Use async flag in setValue method of property bindings
- Fixed issue with updating the binding value

Change-Id: I48b87b5c8f1414b05138b4cb6cc2bbe874e13deb
Merge "[FIX] Databinding: Update asynchronously on twoway property changes"