Move to Open JSON instead of JSON-Java

It's the same thing but with a less fuzzy license:

The original library [1] is licensed under a standard BSD license [2] with an additional line that requires the use of the software only for "non-evil" purposes. Since this is ill-defined, many downstream consumers of this software find this license condition unacceptable. The moral is don't put jokes into legal documents.

Also Tika started to use it so let's be consistent.