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.

(cherry picked from commit f43ffb9a0f71f380f896e1e5c581725e9c08faab)
Signed-off-by: Rohit Yadav <rohit.yadav@shapeblue.com>

Conflicts:
	server/src/com/cloud/storage/VolumeApiServiceImpl.java
	server/src/com/cloud/vm/UserVmManagerImpl.java
	server/src/com/cloud/vm/snapshot/VMSnapshotManagerImpl.java
CLOUDSTACK-7950: AttachIsoCmd shoud give correct messge when trying to attach vmwaretools installer iso on non supported guestvm deployed by ISO

(cherry picked from commit 4ff3130becd50ab8d44864b651c1b1e235d67e6f)
Signed-off-by: Rohit Yadav <rohit.yadav@shapeblue.com>
CLOUDSTACK-7959: fixed 'qemu-img convert' compat issue

Backported using fix 03daae571b44354d31913c7e0ecb9e1f64cdcd55 by
Will Stevens <wstevens@cloudops.com>

Signed-off-by: Rohit Yadav <rohit.yadav@shapeblue.com>