Moved GWT Compatible implementations to super-source

This is mostly just moving files around. The GWT compat classes have been moved to ~/resources/.../super/* and a <super-source> element has been added to the module config. This will make the classes show up as GWT Emulated classes rather than replacements for things that may be on the classpath at compile time.

This fixes compile problems with Gradle, which attempts to re-compile the source files into the local build folder where they take precedence over the "real" class files.