ui: Display IPv6 address accroding to RFC 2732

Previously the IPv6 addresses were shown as they were. To point out that
they are IPv6 addresses they are now shown according to RFC 2732 in [].
This patch covers the basic IPAddress class and the status page.

Change-Id: Iaf43850e3bc18ef771892f2ca03dc9905b99e8bb
Bug-Url: https://bugzilla.redhat.com/show_bug.cgi?id=981279
Signed-off-by: Fabian Deutsch <fabiand@fedoraproject.org>