webadmin: Setup networks- limiting 'network label' text width

LabelWithTooltip is used to limit the width of the label name.
In case the name width is bigger than the limited width (in
pixels), the name is trimmed and '...' are add to it.
The tooltip displays the whole name.

Change-Id: I7315c42d39969de8eaa0c922b1f25050195ec352
Bug-Url: https://bugzilla.redhat.com/1084748
Signed-off-by: Alona Kaplan <alkaplan@redhat.com>