Fix Jenkins build.

Prevent gradle from using -sources.jar as a build dependency by
depending on strong-remoting-android as @jar for compilation.

Other changes:

Unpack -source.jars used by javadoc into `build/javadoc-sources` instead of
build/sources/javadoc-deps.

Rename configurations from includeSources to subSources, includeJavadocs
to subJavadocs.

Log compiler inputs to help with troubleshooting in the future.