Support JRuby (w/ TLS)

Using https://github.com/sensu/sensu-em allows the Sensu transport to work on JRuby, w/ TLS. Need to fork EM to be more aggressive w/ changes to enable `start_tls()`, https://github.com/sensu/sensu-em/commit/cfab68e2051660288a3435a5ff7731090d7c5741