"Deep" validation, part 1: add a boolean flag to FullData

The goal: even if the container fails (array or object), we try and validate
children anyway.

Add a flag to FullData telling whether the validation is deep (false by
default). Make ValidationProcessor account for this flag, test it.

Make all FullData constructors relay that flag.

Signed-off-by: Francis Galiegue <fgaliegue@gmail.com>
JsonValidator: message bundle fix

Signed-off-by: Francis Galiegue <fgaliegue@gmail.com>
Json{Schema,Validator}: add methods to do a "deep" validation

That is, even if, say, an array is invalid, array elements will be validated
anyway.

Requested by issue #62.

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