Update NG-UI Dockerfile to force uncaching of deb package

Change-Id: Idebac79741dc60563ab234eb654b823c6d1bf120
Signed-off-by: garciadeblas <gerardo.garciadeblas@telefonica.com>
diff --git a/docker/NG-UI/Dockerfile b/docker/NG-UI/Dockerfile
index 628e3da..d07c337 100644
--- a/docker/NG-UI/Dockerfile
+++ b/docker/NG-UI/Dockerfile
@@ -38,6 +38,7 @@
     DEBIAN_FRONTEND=noninteractive apt-get update && \
     DEBIAN_FRONTEND=noninteractive apt-get install -y nodejs
 
+ARG CACHE_DATE=not_a_date
 ARG OSM_NGUI_URL
 
 RUN curl $OSM_NGUI_URL -o osm_ngui.deb