exclude directories owned by the filesystem package

hacky see: chef#666

could really do with omnibus passing in config file options
much as the brilliant fpm does

lib/omnibus/packagers/rpm.rb

@@ -396,7 +396,7 @@ def create_rpm_file
     #
     def build_filepath(path)
       filepath = rpm_safe("/" + path.gsub("#{build_dir}/", ""))
-      return if config_files.include?(filepath)
+      return if config_files.include?(filepath) || filesystem_directories.include?(filepath)
       full_path = build_dir + filepath.gsub("[%]", "%")
       # FileSyncer.glob quotes pathnames that contain spaces, which is a problem on el7
       full_path.delete!('"')