bndautomanifest (Java 9 module -> OSGi)

In gradle 3.4, there is now [support for separate api and implementation dependencies](https://docs.gradle.org/current/userguide/java_library_plugin.html).

```gradle
dependencies {
api 'commons-httpclient:commons-httpclient:3.1'
implementation 'org.apache.commons:commons-lang3:3.5'
}
```

Soon (Q2 2017), it will also [support declaring which packages are API](https://discuss.gradle.org/t/will-java-library-get-support-for-declaring-api-packages/21845).

```gradle
api {
exports 'com.somepackage'
}
```

Once this ships, we will create a plugin, `osgi.bndautomanifest`, which will use this metadata to automatically configure `osgi.bndmanifest`.

This way any library with Java 9 module metadata can easily support OSGi. Also, the `api` and `implementation` separation allows gradle to enforce that the implementation details aren't accidentally leaking into the api.