CLOUDSTACK-6402: Fix StopCommand so that VMs are not removed accidentally as part of vmsync
Added a new flag 'checkBeforeCleanup' to StopCommand based on which check is done to see if VM is running in HV host.
If VM is running then in this case it is not stopped and the operation bails out.
Also modified the MS code to call the StopCommand with appropriate value for the flag based on the context.
Currently it is only set to 'true' when called from the new vmsync logic based on powerstate of VM. For rest it
is set to 'false' meaning no change in behaviour.