Create a p2 repository for the Faracon IDE during the maven/Tycho build

[kbirken]

The faracon tool will not only be usable as command-line tool, but also from the Eclipse IDE. Therefore it is necessary to provide a P2 repository (aka update site) to the build which allows to install faracon as one or more Eclipse features.

This issue covers:

• implementing a Eclipse project of type "update site"
• adding it to the maven build so that a p2 repository is created during each build

This is A300.1.