Attach classes as separate Jar

This enables including the project as dependency when developing
extensions:

<dependencies>
    <dependency>
        <groupId>sword</groupId>
        <artifactId>sword-fedora</artifactId>
        <version>1.4.0</version>
        <classifier>classes</classifier>
    </dependency>
</dependencies>

Note that you need to `mvn install` the artifact to your local
repository.
Prepare 1.4.0 release

Made corrections to internal API that might break existing extensions compiled against older versions.
Prepare 1.4.1 development iteration