ADODB_FETCH_DEFAULT should be treated as ASSOC

Ensures that the recordset is returned in the default provided by the
PHP driver as per the documentation.

Fixes #886

adodb.inc.php

@@ -4273,9 +4273,7 @@ function getAssoc($force_array = false, $first2cols = false)
 			switch ($showArrayMethod) {
 			case 0:
 
-				if ($fetchMode == ADODB_FETCH_ASSOC
-				||  $fetchMode == ADODB_FETCH_BOTH)
-				{
+				if ($fetchMode != ADODB_FETCH_NUM) {
 					/*
 					* The driver should have already handled the key
 					* casing, but in case it did not. We will check and force