Properly recognize the development environment.

refs #3736

core/Piwik.php

@@ -671,7 +671,7 @@ class Piwik
 		$messages[] = true;
 
 		// ignore dev environments
-		if(file_exists(PIWIK_INCLUDE_PATH . '/.svn'))
+		if(file_exists(PIWIK_INCLUDE_PATH . '/.git'))
 		{
 			$messages[] = Piwik_Translate('General_WarningFileIntegritySkipped');
 			return $messages;