Use `marquez.jar` as dependency in custom `jvm` app

[wslulciuc]

Let's write docs on how to use marquez.jar as dependency in you custom jvm app> The outline should include:

1. Add marquez.jar as dependency via gradle
2. Use marquez.api libs for extending the API (with custom endpoints)
3. Use marquez.db to define custom db schema (optional) with custom db model (separate from Marquez)
4. Define marquez.App to extend functionality