[XWiki V2] Componentizing XWiki with Plexus

Hi, I've committed in the Sandbox a first shot at componentizing XWiki. The idea is to have concrete examples so that: 1) you can all see how it's meant to work 2) to validate we can use Plexus without having a single import on plexus in our components For 2), I can say it's been successful so far. I've grouped all Plexus stuff in the xwiki-plexus module and that's the only place where there are plexus imports. If we want to use another component system we should be able to do the same (provided that other component system is transparent too). Some more information: * Components are described in components.xml files (check them out) * I haven't committed the plexus.xml file that goes in xwiki-platform- web/standard/src/main/webapp/WEB-INF. See attached. There's plenty more to say but it'd be great if you could check this out and ask questions here and we'll go from there. I'm really happy with the result. I think it makes writing components a breeze and I really like the separation of concerns. Let's get all your questions answered and then we can decide how we want to integrate this in a XWiki release. Thanks -Vincent