fix logger implementation and test

lib/private/log.php

@@ -154,6 +154,6 @@ class Log implements ILogger {
 		$message = strtr($message, $replace);
 
 		$logger = $this->logger;
-		$logger::write($app, $message, $level);
+		call_user_func(array($logger, 'write'), $app, $message, $level);
 	}
 }

tests/lib/logger.php

@@ -19,7 +19,7 @@ class Logger extends \PHPUnit_Framework_TestCase {
 
 	public function setUp() {
 		self::$logs = array();
-		$this->logger = new Log($this);
+		$this->logger = new Log('Test\Logger');
 	}
 
 	public function testInterpolation() {