Add debian/apertis/copyright

Signed-off-by: Dylan Aïssi <dylan.aissi@collabora.com>

debian/apertis/copyright

+Format: https://www.debian.org/doc/packaging-manuals/copyright-format/1.0/
+
+Files: *
+Copyright:
+ 2019 Collabora Ltd.
+ 2019 Peter Senna Tschudin
+License: MPL-2.0
+
+Files: tools/*
+Copyright: 2019, Peter Senna Tschudin
+ 2019, Collabora Ltd.
+License: MPL-2.0