* Update existing test for review button field name, remove obsolete save review test
* Move test classes to tests/php to differentiate from behat
* Add behat build to Travis configuration
- Automatically creates a ContentReviewNotificationJob to run the next day if
the queuedjobs module exists
- Does nothing if the queuedjobs module does not exist, to ensure it is optional
- Update composer to suggest queuedjobs module, and updated docs to reflect both
ways of configuring the module
