add: Script for retrieving a recent version of Jetty
Importing upstream Jetty jetty-9.2.1.v20140609

Imported packages:
* http
* io
* security
* server
* servlet
* util

Removed for compilance:
* Packages:
  - org.eclipse.jetty.server.session.jmx
  - org.eclipse.jetty.server.handler.jmx
  - org.eclipse.jetty.server.jmx
  - org.eclipse.jetty.servlet.jmx

* Classes:
  - org.eclipse.jetty.util.log.JettyAwareLogger
  - org.eclipse.jetty.util.log.Slf4jLog
  - org.eclipse.jetty.server.Slf4jRequestLog