pre-release packaging/CI fixes

Fixes to integrate Traprain into Apertis's QA and CI system.

- Need a 'NEWS' file so 'make distcheck' can pass.
- Create a debian/changelog so we can build pre-release packages.
- When building from not released version, ChangeLog is generated during
  the build process. Update extend-diff-ignore so dpkg-buildpackage
  won't complain about it.

Signed-off-by: Guillaume Desmottes <guillaume.desmottes@collabora.co.uk>
Reviewed-by: Sjoerd Simons <sjoerd.simons@collabora.co.uk>
Differential Revision: https://phabricator.apertis.org/D4301

NEWS

+Initial release of Traprain 0.1.0
+================================
+
+Major changes:
+ • Initial version of the project
+ • Not API stable

debian/changelog

+traprain (0.0.1-0co1) UNRELEASED; urgency=medium
+
+  * Pre release build.
+
+ -- Guillaume Desmottes <guillaume.desmottes@collabora.co.uk>  Tue, 13 Sep 2016 09:02:48 +0200

debian/source/options

-extend-diff-ignore = ^git\.mk$|^\.arcconfig$
+extend-diff-ignore = ^git\.mk$|^\.arcconfig$|^ChangeLog$