ValidationConfiguration*: add the ability to use/not use "format"

Signed-off-by: Francis Galiegue <fgaliegue@gmail.com>
ProcessorChain: rename method, simplify, give meaningful .toString()

Well, meaningful. It needs to be meaningful for individual processors as well,
which is not really the case at this moment!

Signed-off-by: Francis Galiegue <fgaliegue@gmail.com>
Replace processors' .toString() with more sane representations

Signed-off-by: Francis Galiegue <fgaliegue@gmail.com>
ValidatedPaths: get rid of the lock, use synchronized() instead

The code is much more simple as a result, and equally thread safe. Since these
paths are fetched from the cache, they are guaranteed to be the same object for
the same schema.

Signed-off-by: Francis Galiegue <fgaliegue@gmail.com>