[UWS,TAP] Externalize `org.json`.

`org.json` was included in the sources of UWS-/TAP-Lib because of a manual
small correction. This is no longer needed. So this library is now a dependency
(included in the generated JAR). This has also been upgraded to the version of
August 2018.

_This commit aims to reproduce the original content of the Pull Request #38
 by @vforchi ._