Enable monitoring of clients' access time

[jjg-123]

https://oa4mp.org/server/dtd/server-dtd-service-tag.html

Need to set monitorEnable="true" and set the interval to e.g. monitorInterval="2 hr" in the service tag

[bbockelm]

@jjg-123 - can you please send in a PR along these lines?