Define stable module name

As a preparation step for Java 9 and JPMS (Jigsaw), all Jenetics modules should define a stable module name in the `MANIFEST.MF` file by adding a `Automatic-Module-Name` entry.

```
Automatic-Module-Name: io.jenetics.jpx
```

*See:*
* [Java SE 9 - JPMS automatic modules](http://blog.joda.org/2017/05/java-se-9-jpms-automatic-modules.html)