function setMeta(name, content) {
      mapExistingElement(name);

      if (!metaElements[name]) {
        var newMeta = angular.element('<meta name="' + name + '" content="' + content + '"/>');
        head.append(newMeta);
        metaElements[name] = newMeta;
      }
      else {
        metaElements[name].attr('content', content);
      }

      return function () {
        metaElements[name].attr('content', '');
        metaElements[name].remove();
        delete metaElements[name];
      };
    }
@ngdoc method
@name $$mdMeta#setMeta

@description
Creates meta element with the 'name' and 'content' attributes,
if the meta tag is already created than we replace the 'content' value

@param {string} name meta tag 'name' attribute value
@param {string} content meta tag 'content' attribute value
@returns {function} remove function