Docker tag 6 to be used by default in installer and in dockerhub

Change-Id: I637a32d63f171773ad947d4dd2373b1a04f1b28c
Signed-off-by: garciadeblas <gerardo.garciadeblas@telefonica.com>
diff --git a/docker/mk/Makefile.include b/docker/mk/Makefile.include
index a6df090..e19c753 100644
--- a/docker/mk/Makefile.include
+++ b/docker/mk/Makefile.include
@@ -4,7 +4,7 @@
 
 all: build
 
-TAG ?= 5
+TAG ?= 6
 
 REPOSITORY_BASE ?= http://osm-download.etsi.org/repository/osm/debian
 RELEASE         ?= ReleaseFOUR-daily