Shut down extractor when web app shuts down (Issue TeamDewberry/jmxdatamart#32)

Address issue TeamDewberry/jmxdatamart#32 (https://github.com/TeamDewberry/jmxdatamart/issues/32) by stopping the Extractor when the Extractor web application is shutdown.  Additionally, I removed Guice servlets because we're not really serving up any content (URLs).