Re-define QA phase leveraging staging repositories

Now that the new maven repository based on nexus is available, we can finally implement a better QA phase. I'm thinking about providing a proper maven profile for hudson to run against the staging repository. That would allow us to do what follows at code freeze:

• verify all green (blue) on hudson against trunk
• tag every changed components (spi, common, fw, ci, stacks) and mvn deploy them
• close the temporary staging repository/repositories making the artifacts move to the shared staging repo
• quickly re-start hudson against the staging repository
• get a full clear run on hudson (starting with a local repository cleanup)
• promote the artifacts to the release repository