Offer comprehensive D-I and jvmstat use examples.

This commit introduces two new examples for users:

1. Is a complete end-to-end workflow using dependency injection of
   metrics to show that it both possible and easy to do.

2. A complete jvmstat export workflow as defined in the _README.md_
   for the project.
Merge pull request #22 from prometheus/feature/documentation/add-examples-for-guice-and-jvmstat

Offer comprehensive D-I and jvmstat use examples.