Add support for COVERALLS_PARALLEL
Add support for COVERALLS_PARALLEL

See https://docs.coveralls.io/api-reference and https://docs.coveralls.io/parallel-build-webhook

hpi-swa/smalltalkCI,hpi-swa/smalltalkCI,hpi-swa/filetreeCI,fniephaus/filetreeCI,fniephaus/filetreeCI,hpi-swa/filetreeCI,hpi-swa/filetreeCI,fniephaus/filetreeCI