Allow web service specifications without the query endpoint

[chad-earthscope]

The web service specifications in the config file require the full specification to the query endpoint. It would be convenient to allow a service to be specified in any of these equivalent variations:

availability-url=http://service.iris.edu/fdsnws/availability/1/query
availability-url=http://service.iris.edu/fdsnws/availability/1/
availability-url=http://service.iris.edu/fdsnws/availability/1

Beyond convenience, ROVER may in the future wish to consult a service's WADL or version or alternate endpoint of the same general service. In these cases the query part would need to be removed.