Make Create Cluster dialog take images from IR

Right now when Savanna shows Create Cluster dialog, shows image list taken
directly from glance. That is a wrong behaviour, Savanna should take image
list from Image Registry. That commit fixes the issue.

Change-Id: Ie2c804e48cf9d181081c4e7e1861a0ec9cb446f6
Merge "Make Create Cluster dialog take images from IR"