Copyright for nplan source package in Xenial

Format: http://www.debian.org/doc/packaging-manuals/copyright-format/1.0/

Files: *
Copyright: 2016 Canonical Ltd.
License: GPL-3.0
 On Debian systems, the complete text of the GNU Lesser General
 Public License version 3 can be found in "/usr/share/common-licenses/GPL-3".