Added code to disable snapshot buttons for SCVMM VMs.

https://bugzilla.redhat.com/show_bug.cgi?id=1141174
https://bugzilla.redhat.com/show_bug.cgi?id=1141375

@dclarizio please review/test.
@h-kataria  
Every SCVMM virtual machine has a type value of 'VmMicrosoft'. 
The vendor property is pulled from the OS table on the VM so it can be one of many vendor types.
I recommended comparing the VM type to the string 'VmMicrosoft'