Fix Ubuntu Artful and Ubuntu Bionic Dockerfiles

Explicitly install init dependency

Author: alessfg

tests/dockerfiles/Dockerfile.ubuntu-artful

@@ -7,6 +7,7 @@ RUN apt-add-repository -y ppa:ansible/ansible && apt-get update && apt-get insta
     ansible \
     apt-transport-https \
     curl \
+    init \
  && rm -rf /var/lib/apt/lists/*
 
 RUN echo "[local]\nlocalhost ansible_connection=local" > /etc/ansible/hosts

tests/dockerfiles/Dockerfile.ubuntu-bionic

@@ -7,6 +7,7 @@ RUN apt-add-repository -y ppa:ansible/ansible && apt-get update && apt-get insta
     ansible \
     apt-transport-https \
     curl \
+    init \
  && rm -rf /var/lib/apt/lists/*
 
 RUN echo "[local]\nlocalhost ansible_connection=local" > /etc/ansible/hosts