Add 'debian' subdirectory for building dpkg packages

Adding this 'debian' subdirectory will allow users to build
binary packages using 'dpkg-buildpackage' and related tools.

Tested so far on Debian unstable and 9 as well as Ubuntu 17.04
and 17.10 on OpenSuSE Build Service.

debian/rules

@@ -0,0 +1,18 @@
+#!/usr/bin/make -f
+
+# Uncomment this to turn on verbose mode.
+#export DH_VERBOSE=1
+
+DEBIAN  := $(shell dpkg-parsechangelog | grep ^Version: | cut -d' ' -f2)
+DEBVERS := $(shell echo '$(DEBIAN)' | cut -d- -f1)
+VERSION := $(shell echo '$(DEBVERS)' | sed -e 's/[+-].*//' -e 's/~//g')
+
+# This has to be exported to make some magic below work.
+#export DH_OPTIONS
+export DEB_BUILD_MAINT_OPTIONS = hardening=+all
+
+%:
+	dh $@ --with autoreconf
+
+override_dh_auto_test:
+	# skip 'make test' as currently it expects config/log in system paths