code: function changePassword(oldPassword, newPassword, callback) {
        var cb = callback || angular.noop;
  
        return User.changePassword({id: currentUser._id}, {
          oldPassword: oldPassword,
          newPassword: newPassword
        }, function (user) {
          return cb(user);
        }, function (err) {
          return cb(err);
        }).$promise;
      }
docs: @ngdoc method
  @name changePassword
  @methodOf auth.service:Auth
  @description
  Change password
  
  @param {String} oldPassword The old used password
  @param {String} newPassword The new password to use
  @param {Function} [callback] A callback
  @return {Promise} The promise of the User service