webadmin: Fix pm policy checkbox label width

Fixes PM policy checkbox label witdth in Power Management tab in Host
Detail popup. This problem appears only in Firefox 31 on RHEL 6.

Change-Id: I9731f94ca73f4f1eb06b2c6ddb409953255565dc
Bug-Url: https://bugzilla.redhat.com/1148868
Signed-off-by: Martin Perina <mperina@redhat.com>