Fixed test for non-Unix.

  This test will skip execution if /bin/ls isn't present, or
 isn't executable.
  Updated to use new API.

  The expand_variables method uses a Templer::Site object.
  Fetch the plugin by name - using mixed case too.

  This ensures that formatter-lookup isn't case sensitive.
  Added notes for porting.

  This was for ensuring all is OK on windows.