The new JSON library resources loader works.

- Not faster than XML because … work on the JSON loader also impacted
XML loading that is now … faster than JSON.
- The speed gain comes from the fact behaviors are now loaded when
needed (deferred loading) instead of when encountered in the config.
- However the time gained is lost elsewhere.
- JSON uses the POJO mode of Jackson, not the fastest thing on earth.
May be create a real parser later to gain speed.