UI: set the default initial run to false in RunOnce dialog

We change the default to false only if the is_initialized flag is true
(ie the user already run/initialize the VM),
Assuming that the user don't want to re-initialize the VM again.

Change-Id: I2ac2eeee70d1fb4db2712b5407ee3e778e7293c1
Bug-Url: https://bugzilla.redhat.com/1051041
Signed-off-by: Shahar Havivi <shaharh@redhat.com>