Description of problem:
After upgrading from 3.0 to 3.1 and entering the user-portal attempting to perform operations on an existing VM that was already configured with user as PowerUser role fails with "User is not authorized to perform this action".

How reproducible:
?

Steps to Reproduce:
1. Create a VM with a disk and assign a user to it as PowerUser role (make sure user does not have any other permissions) on 3.0
2. Enter user portal with user and run the VM (this works)
3. Upgrade to 3.1
4. Login to user portal and try to run VM or perform any other operation on it - fails due to permission error as diskCreator role was not added to the user
  
Actual results:
Unable to perform operations on VM with disk after upgrade without assigning diskCreator permissions manually to user

Expected results:
Users that were able to perform operations before upgrade should be able to perform the same operations after the upgrade without further permissions