don't create CR if there is no diff
An unmergeable change request can not be commited
Merge remote-tracking branch 'ncharles_origin/proto/workflows' into proto/workflows
Merge remote-tracking branch 'FAR/proto/workflows' into proto/workflows

Conflicts:
	rudder-web/src/main/scala/com/normation/rudder/web/snippet/administration/ChangeRequestDetails.scala