2.3/fix doctrine dependency

[brignoni]

This resolves the following issues.

Missing require

• Doctrine\DBAL is not specified as a require in the illuminate\database repo.
  https://github.com/illuminate/database/blob/master/composer.json
• Illuminate\Database\Schema\Builder depends on Doctrine\DBAL\Schema\MySqlSchemaManager
• So I added it to our composer.json

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 - Unknown enum database type in migration file / Doctrine issue laravel/framework#1346
• Error when mapping database enum field type - Error when mapping database enum field type symfony/symfony#866

[brignoni]

Closing. I am going to submit this to the illuminate/database repo.

[brignoni]

Reopening because the guys at Laravel won't accept it as a direct dependency of illuminate database. They explained its a suggested dependency. So we do need to add the require to PyroCMS.

This is the attempted PR on laravel/framework
laravel/framework#2020
This is a related issue that explain why the don't accept certain direct dependencies.
laravel/framework#1886

[brignoni]

That was quick! Thanks!