Description of problem:
The default for group ownership for a vm or template is "nothing selected". If you assign that template to a group, and want to change it back to the default, it is not possible to choose "nothing selected", only another group.

Version-Release number of selected component (if applicable):
5.8.0.17.20170525183055_6317a22

How reproducible:
100%

Steps to Reproduce:
1.Select a template and click "set ownership" and assign to a group. save.
2.Go back into the "set ownership" menu. 
3.Try to set the template ownership back to the default.

Actual results:
The is no option to select "nothing selected" 

Expected results:
We should be able to change this back in the event someone inadvertently assigns the wrong template to a group and wants to change it back or if the ownership strategy changes.

Additional info: