Optimize Dockerfile statements order for caching

Dockerfile

@@ -1,16 +1,17 @@
 FROM openjdk:8-jre-alpine
 
+RUN apk update && apk add bash && rm -rf /var/lib/apk/* /var/cache/apk/*
+
 VOLUME /etc/mxisd
 VOLUME /var/mxisd
 EXPOSE 8090
 
-RUN apk update && apk add bash && rm -rf /var/lib/apk/* /var/cache/apk/*
-ADD build/libs/mxisd.jar /mxisd.jar
-ADD src/docker/start.sh /start.sh
-
 ENV JAVA_OPTS=""
 ENV CONF_FILE_PATH="/etc/mxisd/mxisd.yaml"
 ENV SIGN_KEY_PATH="/var/mxisd/sign.key"
 ENV SQLITE_DATABASE_PATH="/var/mxisd/mxisd.db"
 
 CMD [ "/start.sh" ]
+
+ADD src/docker/start.sh /start.sh
+ADD build/libs/mxisd.jar /mxisd.jar