userportal,webadmin: webadmin fixes for VM dialog

In FR locale new VM/pool dialog had some issues. Fixed by making the dialog
bigger and setting the proper style to SerialNumberPolicyWidget's checkbox.

Change-Id: I7e8659f3aee8d8ce3a67c97c9fda2d2546175f0c
Bug-Url: https://bugzilla.redhat.com/1123735
Signed-off-by: Tomas Jelinek <tjelinek@redhat.com>