[feature] Master slave connection

[fureszpeter]

Changes proposed in this pull request:

• EntityManagerFactory::create avoid re-parse the config
• Can handle MasterSlaveConnection (http://www.doctrine-project.org/api/dbal/2.0/class-Doctrine.DBAL.Connections.MasterSlaveConnection.html)

Important Notes

Since Laravel support only one slave (read-only) connection, not completely compatible with Laravel database.php

Differences:

_Doctrine version:_

            'read' => [
                [ //<==Please note, we need to add multiple arrays here!
                    'host' => env('DB_HOST_R', 'localhost'),
                    'database' => env('DB_DATABASE_R', ''),
                    'username' => env('DB_USERNAME_R', ''),
                    'password' => env('DB_PASSWORD_R', ''),
                ],
            ],

_Laravel version:_

            'read' => [
                    'host' => env('DB_HOST_R', 'localhost'),
                    'database' => env('DB_DATABASE_R', ''),
                    'username' => env('DB_USERNAME_R', ''),
                    'password' => env('DB_PASSWORD_R', ''),
            ],

[patrickbrouwers]

Can you retarget your work to 1.2? Note that 1.2 shares PDO connections with Laravel. I don't know how much that will change for your work?

[guiwoda]

@fureszpeter I don't think this should be extracted to a whole class.
This could live inside the EntityManagerFactory, as no other code will need to call it. Plus, a big, big, BIG 👎 to utility (static) classes.

[patrickbrouwers]

Replaced by #214