* Allow for optional can permission method for content review
* Content Review permission logic
With the new `canReviewContent()` permission checker we only need to check the permission is set for the user and `canBeReviewedBy()` will always check if the page object is due for review by its owner.
Thus removed redundant logic in `canUseReviewContent()` and accordingly renamed the class filename for additional context.
Co-authored-by: Jared Dreyer <jared.dreyer@silverstripe.com>
* 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
