code: function template(filePath, locals, fn) {
      filePath = path.join(getConfig('template.folder'), filePath  + '.' + getConfig('template.extension')); // i.e. index -> index.ejs
      return cons[getConfig('template.engine')].call(null, filePath, locals, fn);                            // i.e. cons.swig('views/page.html', { user: 'tobi' }, function(err, html){}
  }
docs: Renders the template and executes callback function.
  @private
  @param {string} filePath - Path of the template file relative to template folder.
  @param {object} locals - Local variables to pass to template
  @param {function} fn - Callback function(err, output)