fixed misspelled name in Persistence Exception

Author: Raaghu

src/Errors/Exceptions/Persistence/PersistenceException.php

@@ -1,11 +1,11 @@
-<?php
-
-namespace PhpPlatform\Errors\Exceptions\Persistence;
-
-use PhpPlatform\Errors\Exceptions\PlatformException;
-
-abstract class PersistenceException extends PlatformException {
-	public function __construct($message = null, $code = null, $previous = null) {
-		parent::__construct ("Persistance", "[P]", $message, $code , $previous );
-	}
+<?php
+
+namespace PhpPlatform\Errors\Exceptions\Persistence;
+
+use PhpPlatform\Errors\Exceptions\PlatformException;
+
+abstract class PersistenceException extends PlatformException {
+	public function __construct($message = null, $code = null, $previous = null) {
+		parent::__construct ("Persistence", "[P]", $message, $code , $previous );
+	}
 }