Include exception message in log entry when session fails to start

lib/base.php

@@ -304,7 +304,7 @@ class OC {
 			self::$session = new \OC\Session\Internal(OC_Util::getInstanceId());
 			// if session cant be started break with http 500 error
 		} catch (Exception $e) {
-			OC_Log::write('core', 'Session could not be initialized',
+			OC_Log::write('core', 'Session could not be initialized. Exception message: '.$e->getMessage(),
 				OC_Log::ERROR);
 			header('HTTP/1.1 500 Internal Server Error');
 			OC_Util::addStyle("styles");