Where are the downloaded Python modules?

Hi,

I'm struggling to find the Python modules that are downloaded by the plugin. With the attached build.gradle, Gradle downloads the `six` module, but then I can't find it anywhere in the `build` directory, including in `build/libs/jython_test.jar`.

I am using Gradle 4.10.1. Could this be a duplicate of #20 ? If so, could I respectfully ask when the pull request in that issue will be integrated into the main jython-gradle-plugin?

Thanks!

Best,
Alexander.

```
hilbert:jython_test koller$ ./gradlew build

> Task :jythonDownload
Downloading Jython library: six with version 1.11.0
Downloading: DefaultExternalModuleDependency{group='null', name='six', version='1.11.0', configuration='default'} from https://files.pythonhosted.org/packages/16/d8/bc6316cf98419719bd59c91742194c111b6f2e85abac88e496adefaf7afe/six-1.11.0.tar.gz
Cannot find parser for content-type: binary/octet-stream -- using default parser.

BUILD SUCCESSFUL in 8s
3 actionable tasks: 3 executed

hilbert:jython_test koller$ jar tf build/libs/jython_test.jar
META-INF/
META-INF/MANIFEST.MF

hilbert:jython_test koller$ find build/
build/
build//jython
build//jython/main
build//jython/test
build//libs
build//libs/jython_test.jar
build//tmp
build//tmp/jar
build//tmp/jar/MANIFEST.MF
```

[Archive.zip](https://github.com/hierynomus/jython-gradle-plugin/files/2636732/Archive.zip)