jni 0.16.0

Rust bindings to the JNI
Documentation
## Overview

Please describe your changes here and list any open questions you might have.

### Definition of Done

- [ ] There are no TODOs left in the code
- [ ] Change is covered by automated [tests]https://github.com/jni-rs/jni-rs/blob/master/CONTRIBUTING.md#tests
- [ ] The [coding guidelines]https://github.com/jni-rs/jni-rs/blob/master/CONTRIBUTING.md#the-code-style are followed
- [ ] Public API has documentation
- [ ] This change is not breaking **or** mentioned in the Changelog
- [ ] The [continuous integration build]https://www.travis-ci.org/jni-rs/jni-rs passes