added BaseNodeFilter

renamed some private vars
added some default values
updated uglifyjs filter to use --no-mangle

This is necessary in order for UglifyJS 1.3.4 to
work since the --mangle option doesn't appear to
exist. If there are earlier versions of UglifyJS
that don't have the --no-mangle option we will
need to figure out compatibility for both.
made integration tests smarter