Description of problem:
Cannot save deselecting cloud providers in "Hosts&Clusters" tab, save button is inactive

Version-Release number of selected component (if applicable):
5.8.0.10

How reproducible:
100%

Steps to Reproduce:
1. Add cloud provider
2. Add role
3. Add group and select cloud provider in "Hosts&Clusters" tab
4. Save group
5. Edit group, deselect provider

Actual results:
Save button is not active

Expected results:
Save button should be active

Additional info:
Works fine in 5.7.2