Clean up Dockerfile

- Try to follow Dockerfile best practices:

  https://docs.docker.com/engine/userguide/eng-image/dockerfile_best-practices/
- Cleanup formatting to make it a bit more readable.

Change-Id: I9b5e13bdb270477ea92c0b101beaa519e5fe6223
Signed-off-by: Chuck Short <charles.short@ericsson.com>
Signed-off-by: Michael Lando <ml636r@att.com>
diff --git a/sdc-os-chef/sdc-sanity/Dockerfile b/sdc-os-chef/sdc-sanity/Dockerfile
index 2b29131..c5421a1 100644
--- a/sdc-os-chef/sdc-sanity/Dockerfile
+++ b/sdc-os-chef/sdc-sanity/Dockerfile
@@ -1,4 +1,4 @@
-FROM ubuntu
+FROM ubuntu:16.04
 
 ARG HTTP_PROXY
 ARG HTTPS_PROXY
@@ -7,12 +7,14 @@
 ENV HTTPS_PROXY ${HTTPS_PROXY}
 
 RUN if [ ! -z ${HTTP_PROXY} ]; then echo "Acquire::http::proxy  \"${HTTP_PROXY}\";" >> /etc/apt/apt.conf; fi && \
+RUN apt-get -y update && \
+    apt-get -y install --no-install-recommends apt-utils && \
+    apt-get install curl \
+                    default-jre 
+                    openjdk-8-jdk
+                    vim && \
+    update-alternatives --set java /usr/lib/jvm/java-8-openjdk-amd64/jre/bin/java
     if [ ! -z ${HTTPS_PROXY} ]; then echo "Acquire::https::proxy \"${HTTPS_PROXY}\";" >> /etc/apt/apt.conf; fi 
-RUN apt-get -y update && apt-get -y install --no-install-recommends apt-utils
-RUN apt-get -y install curl
-RUN apt-get -y install vim
-RUN apt-get -y install default-jre && apt-get -y install openjdk-8-jdk
-RUN update-alternatives --set java /usr/lib/jvm/java-8-openjdk-amd64/jre/bin/java
 
 COPY chef-solo /root/chef-solo/
 COPY chef-repo/cookbooks/. /root/chef-solo/cookbooks/
@@ -22,4 +24,5 @@
 
 COPY startup.sh /root/
 RUN chmod 770 /root/startup.sh
+
 ENTRYPOINT [ "/root/startup.sh" ]