Allow testing with doctrine/common 2.6

Fixed typo

Added Postgres 9.4 platform (DBAL-1143)

MySQL getListTableForeignKeysSQL: use current database if null passed

Features and changes:
* jsonb can be used with: options={"jsonb"=true}
* OVER is no longer reserved
* LATERAL is now reserved

DateInterval Type

Travis: Switch to container-based infrastructure

Ref: https://github.com/doctrine/doctrine2/pull/1466

return result from Doctrine\DBAL\Connection::transactional()

Fix call on non-object in ping() with PDO wrapper

Remove git submodules

Fixes an issue when calling `ping()` where `$this->platform` is null. Happened to me because using the `'pdo'` param bypasses the `connect()` method and the platform is never set without explicitly calling the method.

Not sure if this is the most elegant way to deal with this but it worked enough for my purposes so I figured I should submit a PR.

This reverts commit aa4d483f.

Fix undefined notices within MasterSlaveConnection

To fix the following notice-level errors:

Notice: Undefined property: Doctrine\DBAL\Connections\MasterSlaveConnection::$_conn in vendor/doctrine/dbal/lib/Doctrine/DBAL/Connections/MasterSlaveConnection.php line 154
Notice: Undefined index: slave in vendor/doctrine/dbal/lib/Doctrine/DBAL/Connections/MasterSlaveConnection.php line 165

removed empty line

Remove HHVM-nightly builds

This also simplies the allowed failures for HHVM

Revert the addition of the wrong bin script

Documentation & code styling fixes