Description of problem:
If vm from a vm-pool is running while trying to remove the pool,
the remove of the pool is failed, and user need to remove the pool again.

Version-Release number of selected component (if applicable):
3.6-master

How reproducible:
always 

Steps to Reproduce:
1. create vm pool
2. have a vm from the pool running (for example use prestarted vm)
3. remove vm pool

Actual results:
pool removal fails, need to try again (works on second attempt since vms are down)

Expected results:
pool removed