userportal: add 'update on next restart' dialog

On update running VM such that part of the changed configuration can be
applied only when the VM will be restarted, new dialog is presented with
a proper message and the user can choose whether cpu changes (if exist)
will be applied immediately or later.

Change-Id: Ie2fbede65c57505d1290cd8eb6c3bc239a6eb47d
Signed-off-by: Arik Hadas <ahadas@redhat.com>