License maintenance: GPLv2 -> GPLv2+
Summary:
This is based on https://techbase.kde.org/Projects/KDE_Relicensing for
the individual authors. The only one not found on there is KDAB (hereby
approved).
Reviewers: dvratil
Reviewed By: dvratil
Subscribers: kde-pim
Tags: KDE PIM
Differential Revision: https://phabricator.kde.org/D16136