code: function renderTemplate(contents, data, filename) {
      if (!templateCache.hasOwnProperty(contents)) {
        var jadeOptions = merge.recursive({}, options.jadeOptions, {filename: filename});
        templateCache[contents] = options.jade.compile(contents, jadeOptions);
      }
      var locals = merge.recursive({}, data, {locals: locals});
      return templateCache[contents](data);
    }
docs: render a template string with optional data
  @param  {string} contents template
  @param  {object} data     optional template data
  @param  {object} filename optional template path for importing/mergeing
  @return {string}          rendered template