(TK-110) Added idle timeout setting to proxy 

At some point among the various JIRA tickets, there was some discussion about changing the default idle timeout to something higher -- e.g., 60 seconds -- since we had some well-known clients for which 30 seconds wasn't enough.  Not sure if that was ever agreed upon as a good idea, though, or if it was expected that affected clients would need to specifically make a code change and set a specific value to bump up the timeout, where needed.  @KevinCorcoran do you know?

In any event, I would be inclined to have our code define a default value -- even if it is just 30 seconds for compatibility with Jetty's current implementation -- and make the `.setIdleTimeout` call with that for the case that one isn't specified in the options config so that we aren't surprised by Jetty changing the default out from underneath us in a new release.