Add touch command to create /var/lib/haproxy/server-state #163
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This partially addresses issue #123.
The following warning appears in docker-service-proxy service logs after HAProxy was updated:
[WARNING] 257/231940 (1) : Can't open global server state file '/var/lib/haproxy/server-state': No such file or directory
Adding this touch command to the Dockerfile will create the server-state file in the Docker image and silence this warning.