gedit: GPLv2+ is the correct the `LICENSE`.

gedit: GPLv2+ is the correct the `LICENSE`.

`COPYING` [1] and the file headers, for example [2], say GPLv2+. Only `README` [3] just mentions GPLv2.

[1] http://git.gnome.org/browse/gedit/tree/COPYING?id=dada4388aa0c33486a6d48ee1c8f2adac67abb01
[2] http://git.gnome.org/browse/gedit/tree/gedit/gedit-view-frame.c?id=dada4388aa0c33486a6d48ee1c8f2adac67abb01
[3] http://git.gnome.org/browse/gedit/tree/README?id=3fdf01ec9e0ac5f48d22e7e5d369c81fa357ea49

Signed-off-by: Paul Menzel <paulepanter@users.sourceforge.net>
Signed-off-by: Frans Meulenbroeks <fransmeulenbroeks@gmail.com>