CLOUDSTACK-7688, CLOUDSTACK-7747: restricted various operations for VM with VM snapshots which breaks VM snapshots.
 Now they are informed that they cannot perform the operation.
 To perform operation they have to remove VM snapshots of VM.
CLOUDSTACK-7767: fixed events are not generated for snapshot creation
PR #27 CLOUDSTACK-7767

Fixed events are not generated for snapshot creation #27

This closes #27
PR #26 CLOUDSTACK-7688, CLOUDSTACK-7747

Restricted various operations for VM with VM Snapshots #26

This closes #26