The cluster boot benchmark should the num_cpus function in parallel

[voellm]

The cluster boot benchmark has the following code:

for vm in vms:
metadata = {'machine_type': vm.machine_type, 'num_cpus': vm.num_cpus,
'machine_instance': vm_number}
value = vm.TimeToBoot()

This looks great until you realize vm.num_cpus is a method on the virtual machine which in turn calls RemoteCommand leading to an ssh. When large number of VM's boot the result is a long set of serially run ssh's to each VM. This could be done a lot faster by moving the code into a method and then using RunThreaded.

[cmccoy]

Closed by #73.