shill: expand dbus constants for DHCPv6

This allows multiple DHCPv6 addresses/prefixes and preferred lease times to be
exposed over DBus from shill.  This information is necessary to correctly assign
IPv6 addresses in some cases.

BUG=b:26778228
TEST=shill unit test

Change-Id: I179dc5fd02699f07598e6c7603f45d5d9ebdde52
Reviewed-on: https://chromium-review.googlesource.com/333963
Commit-Ready: Timothy Jennison <tjennison@google.com>
Tested-by: Timothy Jennison <tjennison@google.com>
Reviewed-by: Paul Stewart <pstew@chromium.org>
1 file changed