userportal: introducing create instance

This patch contains the following:
- added the possibility to edit the create instance role in the role view
- created a CommonCurrentUserRole which contains the createInstanceOnly flag
  which is true, if the user has the create_instance action group. Otherwise it
  is false
- added the handling of the createInstanceOnly to the VM dialog
- makes sure that the user queries are being called with the proper action
  groups (create_vm or create_instance)

Change-Id: Ib05736665da4dbed48c9081e34e2bfeade307d1f
Signed-off-by: Tomas Jelinek <tjelinek@redhat.com>