Add an automatic module name

[dmlloyd]

In order to be consumed by modularized downstream projects in a useful way, this project should define an automatic module name. I would suggest that it be defined as org.codehaus.plexus.classworlds. The automatic module name is established by setting the Automatic-Module-Name property in the main section of the JAR manifest.

Normally, a project such as this with no dependencies would be able to add a regular module descriptor immediately. However, since this project deals with class loading, it's likely that this would be a bit bumpy to ramp up. It is likely best to start with just the automatic module name, and move to a full descriptor later when additional downstream testing can be done.