Allow HIS Central to track requests from HydroDesktop

twhitvine[CodePlex]
This would be a nice way of seeing what fraction of requests to our system are from HydroDesktop, and also give a sense of how much HydroDesktop is being used.

From Dave V.: We could set the http-quotreferrerquot and/or quotUserAgentquot code in Hydrodesktop to a recognizable value. When HydroDekstop calls HIS central that will be logged to the web server logs, and it will be recognizable.

No files or tests are named. Start by locating HydroDesktop's requests to HIS Central and determine where request metadata is set; done means requests are consistently recognizable in HIS Central's web-server logs as originating from HydroDesktop.

Written by the indexing model from the issue text.