Minimize use of RUN instructions

Each RUN instruction adds a layer and size to the docker image. This saved about 14MB in my testing against this image.

nginx/Dockerfile

@@ -4,16 +4,14 @@ MAINTAINER bin.yang@intel.com
 COPY default.conf /etc/nginx/conf.d/default.conf
 
 RUN swupd update $swupd_args && \
-    swupd bundle-add nginx $swupd_args
-RUN rm -rf /var/lib/swupd
-
-# forward request and error logs to docker log collector
-RUN mkdir -p /var/log/nginx
-RUN ln -sf /dev/stdout /var/log/nginx/access.log \
-	&& ln -sf /dev/stderr /var/log/nginx/error.log
-
-RUN mkdir -p /var/lib/nginx/
-RUN cp -f /usr/share/nginx/conf/nginx.conf.example /etc/nginx/nginx.conf
+    swupd bundle-add nginx $swupd_args && \
+    rm -rf /var/lib/swupd && \
+    mkdir -p /var/log/nginx && \
+    # forward request and error logs to docker log collector
+    ln -sf /dev/stdout /var/log/nginx/access.log && \
+    ln -sf /dev/stderr /var/log/nginx/error.log && \
+    mkdir -p /var/lib/nginx/ && \
+    cp -f /usr/share/nginx/conf/nginx.conf.example /etc/nginx/nginx.conf
 
 
 VOLUME /usr/share/nginx/html