core : UserVmManager has import_export_vm permission, but there is no such action in UserPortal

UserVmManager has import_export_vm permission, but
there is no such action in UserPortal.

This patch removes the action group from the role.

Change-Id: Ide617dbcb30c517cbe3da2fe832aa021f9f8731a
Bug-Url: https://bugzilla.redhat.com/1002588
Signed-off-by: Ravi Nori <rnori@redhat.com>