Configure Codacy

[matthiasbalke]

We should add a codacy configuration .codacy.yml as described here which configures the following:

• Exclude class .mvn/wrapper/MavenWrapperDownloader.java
• Activate analysis for pull requests

Maybe we can start with setting these options manually within Codacy, because I do have no experience with the file format or the service.

[teverett]

sounds fantastic.

[matthiasbalke]

If possible we could disable the PMD rule forbidding use of System.exit() within the standalone module.