(SERVER-88) catch errors before they get to Jetty

Add a 'catch-all' middleware to both the Master and CA ring handlers
which catches any Exception, logs it, and returns a simple error message
in the response body.  This prevents Exceptions from propagating all the
way out to Jetty - if this happens, Jetty will generate HTML from the
stacktrace and return this to the client.
Unrelated to this ticket, but might be good to purge the `wrap-request-logging` and `wrap-response-logging` middleware now since we have the `access-log-config` feature in `webserver-jetty9`?