fix evaluation of NOLOCK table hint on SQL Server

(cherry picked from commit 69931faa82e985023d6c3c41f47b89230e5f7fc9)
Merge pull request #663 from deeky666/fix-sql-server-nolock-hint-2.4

[DDC-2310] [2.4] Fix evaluation of NOLOCK table hint on SQL Server
[DBAL-717] Fix bug in MasterSlaveConnection with keepSlave option and switch back after transaction.

Conflicts:
	tests/Doctrine/Tests/DBAL/Functional/MasterSlaveConnectionTest.php
Merge pull request #690 from adrienbrault/dbal-717-2.4

Cherry pick to 2.4: [DBAL-717] Fix bug in MasterSlaveConnection with keepSlave option and switch back after transaction.
Release 2.4.3
Bump version to 2.4.4