Illuminate\Database\Schema\Builder depends on Doctrine\DBAL\Schema\MySqlSchemaManager but it was not specified as a require in the Illuminate composer.json. So we need to add it here.
Fix “unknown database type enum requested”

	* Should probably be addressed in Doctrine, if not in Illuminate\Capsule
	* Doctrine 2: Resolving “unknown database type enum requested” - http://wildlyinaccurate.com/doctrine-2-resolving-unknown-database-type-enum-requested
	* Unknown enum database type in migration file / Doctrine issue - https://github.com/laravel/framework/issues/1346
	* Error when mapping database enum field type - https://github.com/symfony/symfony/issues/866