Upgrade to Atmosphere 2.0.3 and other smaller changes

Hello,

Thanks a lot for providing this great example of integrating the Atmosphere Framework with OSGi. I am proposing here a change to upgrade to the latest version of Atmosphere, 2.0.3, that requires Servlet API 3.0. I hope the changes here are acceptable, let me know.

A lot of the smaller changes are just cleanups in the Maven project, and I've also added generation of the sources and javadoc JARs along with the artifacts. 

Best regards,
  Serge Huber.