Can't exclude inner classes because Scala expects them to exist.

With Scala, it's not so easy to exclude the unit tests from the published JARs, unfortunately. The Scala compiler expects specified inner classes to actually exist in libraries.

This means that all JARs in RxJava modules which might be used by Scala have to include all their inner classes. Currently, this just applies to `rxjava-swing`, as far as I can see.

This PR simply removes excluding the unit tests from `rxjava-swing` from the Gradle build.