Switch from PHP 5.6 to 7.1 (task #7636)
Switch from PHP 5.6 to 7.1 (task #7636)

* Updated to new cakephp-utils version that drops support for PHP 5.6
  and PHP 7.0.
* Locked PHPUnit to v6 until CakePHP 3.6 upgrade.

QoboLtd/cakephp-calendar,QoboLtd/cakephp-calendar,QoboLtd/cakephp-calendar