Fix folder permissions for elasticsearch volume

Summary

The readme and start.sh script need to be updated as the folder permissions have to equal 100:101. This is due to the change of the database base image to elasticsearch:5.6-alpine

Behavior

Starting the database container will result in errors:

[WARN ][o.e.b.ElasticsearchUncaughtExceptionHandler] [] uncaught exception in thread [main]
  org.elasticsearch.bootstrap.StartupException: java.lang.IllegalStateException: Failed to create node environment
  Caused by: java.nio.file.AccessDeniedException: /usr/share/elasticsearch/data/nodes
  ...
minimal-deployment_database_1 exited with code 1

Proposed solution

Adjust directory permissions