Bump version to 1.18.11

debian/changelog

@@ -1,3 +1,9 @@
+dpkg (1.18.11) UNRELEASED; urgency=medium
+
+  *
+
+ -- Guillem Jover <guillem@debian.org>  Sun, 31 Jul 2016 16:33:01 +0200
+
 dpkg (1.18.10) unstable; urgency=medium
 
   [ Guillem Jover ]