create maven artifacts and publish to local .m2/

[Jan Galinski]

I can run gradle and see

• io.holunda.testing:camunda-testing-core:0.0.1-SNAPSHOT

in local .2/ dir

I can use this dependency in a maven project

[Lukas Taake]

Artifacts can now be published to local m2 repository with ./gradlew publishToMavenLocal