Adds support for setting the charset in SQLSrv

As seen here => http://technet.microsoft.com/en-us/library/cc626307(v=sql.105).aspx

lib/Doctrine/DBAL/Driver/SQLSrv/Driver.php

@@ -43,6 +43,10 @@ class Driver extends AbstractSQLServerDriver
         if (isset($params['dbname'])) {
             $driverOptions['Database'] = $params['dbname'];
         }
+        
+        if (isset($params['charset'])) {
+            $driverOptions['CharacterSet'] = $params['charset'];
+        }
 
         $driverOptions['UID'] = $username;
         $driverOptions['PWD'] = $password;