Executable WAR and Jetty plugin

I added some entries in the pom.xml to directly run the MELA-AnalysisService via the jetty:run command (enabled by the Jetty plugin), and to create an executable war file to be run as java -jar <app-name>.war -Djetty.port=<an optional port>.

For the creation of the war I added the Main class at the root of this project. It's a generic class and must be extended only if you need specific features.

I haven't tested yet.

-- Alessio