Testing:
  Add Sass support for various utilities (benchmark, profile)

Documentation:
  ! Document Sass module
  Haml::Engine public method documentation could use work

Features:
  #foo.bar[@person] => <div id="foo_person_12345" class="bar person">
  Sass should throw generic errors for undefined constants, not syntax errors
  There should be a way to represent options in-document
  Haml and Sass executables should return meaningful exit codes