jvb: try to use the correct IP as the default server ID

This hopefully fixes WS issues on environment with multiple networks
such as Docker Swarm.

jvb/Dockerfile

@@ -3,7 +3,7 @@ ARG BASE_TAG=latest
 FROM ${JITSI_REPO}/base-java:${BASE_TAG}
 
 RUN apt-dpkg-wrap apt-get update && \
-    apt-dpkg-wrap apt-get install -y jitsi-videobridge2 jq curl iproute2 && \
+    apt-dpkg-wrap apt-get install -y jitsi-videobridge2 jq curl iproute2 dnsutils && \
     apt-cleanup
 
 COPY rootfs/ /