Web Interface for admin is up (wicket4)

It's a bit scruffy (lot of CSS to be fixed) and perhaps with some minor bugs, but a basic web interface for managing registers is there. It takes into account validation, previous conditions and all of that in a coherent way. Validation is also a bit extended, it can handle interesting constructs like narrower defined on an already existing term  and so on.. (plus cardinality, cardinality by language, restricted options, numeric fields...).
Included is also a configurable process engine for transitions among states.

Closes #18