Support different output formats

[php-coder]

I'm using license-maven-plugin to only check the sources when a new PR is submitted. I didn't find a way to get the messages in the machine-readable form (XML/JSON). It would be great to have such feature because it could be used in automatization and integration with external plugins/bots.

[mathieucarbou]

Hi @php-coder,
The plugin uses the maven infrastructure to output and log so there are some formatting out of our control.
Though, we could eventually "bufferize" the logs and at the end of the execution, output the result in some format (json or xml) in a target directory.
This would be a kind of report, that could be used for some reporting tools.

[mathieucarbou]

Implemented in PR #227.

See report examples when running ReportTest

See updated plugin doc: https://mycila.carbou.me/license-maven-plugin/reports/4.2-SNAPSHOT/license-maven-plugin/plugin-info.html