webadmin: Mention host's name in Setup Networks title

Added the host name to the dialog's title, so that users will easily
be aware of which host's networks they're configuring.

Change-Id: Id3eaa163564846f2c24e1e86e49b7ec3879dcf85
Bug-Url: https://bugzilla.redhat.com/1114882
Signed-off-by: Lior Vernia <lvernia@redhat.com>