Makes the CI not dependant on a PHPStan pass so that it can run through to the unit tests
Adds alcaeus/mongo-php-adapter so that composer install can run without ext-mongo. This could be removed again if doctrine/mongodb-odm is upgraded, as in the elchris fork.
Disables the Propel tests as all the Propel code seems to be missing something in the FOS\OAuthServerBundle\Propel\om namespace
Updates the PHPStan configuration including the addition of phpstan-symfony.
Subset of #663. This pull request: