Generate source jars supporting Eclipse Source Bundle format.

When developing eclipse plugins, or any OSGi bundle, it is desirable to create the source attachments for a project as Eclipse Source Bundles. See http://wiki.eclipse.org/Source_Bundles

A source bundle appears in the target platform (the bundles in the runtime) and allows the user to step into the source in debug, view the source, and see the javadoc from the source. All without having to download the source project. Source bundles differ from source attachments in non OSGi projects in that they are part of the target platform, which is resolved dynamically at runtime, not at compile time with the classpath.

It is very easy to extend the maven source plugin to create these source bundles. They are identical to the currently generated jar, with the addition of a few entries in the META-INF/MANIFEST.MF file. So source jars usable as source bundles are also 100% compatible with what is currently generated.

I have already done the work and would be happy to contribute this back if there is any interest.