def build!
      create_output_directory
      spec.source_directories.each { |d| simple_compile_directory(d) }
      compile_files(spec.all_javascript_paths)
      compile_files(spec.all_stylesheet_paths)
      write_manifest
    end
def build!
      create_output_directory
      spec.source_directories.each { |d| simple_compile_directory(d) }
      compile_files(spec.all_javascript_paths)
      compile_files(spec.all_stylesheet_paths)
      write_manifest
    end
Create a new builder. You must pass the specification, full path to the
 source directory and an optional output directory which defaults to
 base_dir + '/build'

 Do the building. This simply delegates to the private methods
 in this class.