Making the different nodes more generic, moving towards combing them into a generic `Process` node.
Combining all of the separate 'compile' and 'minify' stuff into generic 'process' stuff.  Much simpler.
Changing the 'BundleNode' into just a processor which can be called with `.Process("bundle", "output_filename.ext")`.
Replacing the `HashFileNamesNode` node with a generic processor which can be called with `.Process()`.  Required passing the pipeline into the `Processor.__init__()` method.