Can't interact with 'Ceph RBD for images' checkbox when enviroment contains controllers .

Detailed bug description:
 Fuel UI doesn't give the opportunity interact with 'Ceph RBD for images' checkbox when enviroment contains controllers.

Steps to reproduce:
 1. Create a new OpenStack environment with default configuration.
 2. Visit enviroment dashboard and add new node with controller role.
 3. Go to: Settings>Storage, activate 'Ceph RBD for images (Glance)' checkbox and click to 'Save Changes' button.

Expected results:
 All settings changes must be activated and saved.

Actual result:
 Checkbox 'Ceph RBD for images (Glance)' is not available for editing with warning message: The enviroment contains controllers.

Reproducibility:
 For all types of enviroments.

Workaround:
 1. Visit enviroment dashboard and remove all nodes with controller role.
 2. Go to: Settings>Storage, activate 'Ceph RBD for images (Glance)' checkbox and click to 'Save Changes' button.
 3. Go back to enviroment dashboard and add new node with controller role.

Impact:
 This bug interferes normal interaction with 'Ceph RBD for images' checkbox.

Description of the environment:
 Output of host:8000/api/version/: http://paste.openstack.org/show/490382/
 Output of shotgun2: http://paste.openstack.org/show/490381/
 Operating System: http://paste.openstack.org/show/490384/
 Reference architecture: HA
 Network model: Neutron+VLAN
 Related projects installed: Any