add SyslogHandler to Monolog

usage example:

   $log = new Logger('application');
   $syslog = new SyslogHandler('myfacility', 'local6');
   $formatter = new LineFormatter("%channel%.%level_name%: %message% %extra%");
   $syslog->setFormatter($formatter);
   $log->pushHandler($syslog);

tests/Monolog/Handler/SyslogHandlerTest.php

@@ -0,0 +1,37 @@
+<?php
+
+/*
+ * This file is part of the Monolog package.
+ *
+ * (c) Jordi Boggiano <j.boggiano@seld.be>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Monolog\Handler;
+
+use Monolog\Logger;
+
+class SyslogHandlerTest extends \PHPUnit_Framework_TestCase
+{
+    public function testConstruct()
+    {
+      $handler = new SyslogHandler('test');
+      $this->assertInstanceOf('Monolog\Handler\SyslogHandler', $handler);
+
+      $handler = new SyslogHandler('test', LOG_LOCAL1);
+      $this->assertInstanceOf('Monolog\Handler\SyslogHandler', $handler);
+
+      $handler = new SyslogHandler('test', 'local1');
+      $this->assertInstanceOf('Monolog\Handler\SyslogHandler', $handler);
+
+    }
+
+    public function testConstructInvalidFacility()
+    {
+      $this->setExpectedException('UnexpectedValueException');
+      $handler = new SyslogHandler('test', 'unknown');
+    }
+
+}