updates sandbox component 'modelbuilder-addon' to be compatible with latest opennlp-tools release (#62)

- adjusts opennlp-tools to 2.1.0
- adjusts parent project (org.apache.apache) to version 18
- adjusts Java language level to 11
- improves resource handling of streams
- removes funny pseudo JUnit-test which was effectively doing nothing
- removes unused imports
15 files changed