Description of problem:
There is no indication if the disk's Storage Domain is active or not.
When the user run a VM or try to use the disk, the engine sends a CDA message indicating that the Storage Domain is inaccessible, though it would be great if the user could see that before in the disks subtab under vms or in the main tab of disks.

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


How reproducible:
100%

Steps to Reproduce:
1. Create a VM
2. Add a disk on Storage Domain A
3. Add another disk on Storage Domain B
4. Move Storage Domain B to maintenance
5. Try to run the VM

Actual results:
You will get a message that the Storage Domain is not accessable

Expected results:
We should also have an indication in the GUI that the Storage Domain which the disk is based on is not accessible (Something like an explanation mark)

Additional info:
We should add an attribute in the disk business entity of the Storage domain status