Create fatSources/fatJavadocs for publishing

[KinComet]

Hi.
With

        create<MavenPublication>("mavenJar") {
            from(components["shadow"])
            artifact(tasks.sourcesJar) { classifier = "sources" }
        }

There's no javadocs and sources from the dependencies.
I wish I could include, and relocate them to the artifacts.
How to make it possible?

[Goooler]

Duplicate of #41