Merge branch 'lintian-fixes' into 'master'

Fix some issues reported by lintian

See merge request !3

debian/compat

-10

debian/control

 Source: firewall
 Section: net
-Priority: extra
+Priority: optional
 Maintainer: Autistici/Inventati <debian@autistici.org>
-Build-Depends: debhelper (>= 7)
+Build-Depends: debhelper-compat (= 12)
 Standards-Version: 3.8.0.1
 
 Package: firewall
@@ -10,4 +10,3 @@ Architecture: all
 Depends: ${misc:Depends}, iptables, ipset
 Description: A/I Firewall Script
  Automatically maintain local firewalls for A/I servers.
-

debian/rules

@@ -5,4 +5,3 @@ export DH_OPTIONS
 
 %:
 	dh $@
-

debian/source/format

+3.0 (native)