title: Wrong month number when parsing datetime string with date filter
body: <p>I'm trying to setup <a href="http://logstash.net/" rel="nofollow">logstash</a> on my machine.</p>
  
  <p>The problem is I can't correctly parse logdate using date filter:</p>
  
  <p>Here is config file (<code>test.conf</code>) to reproduce this issue:</p>
  
  <pre><code>input {                                                                                                                
    stdin { }                                                                                                            
  }                                                                                                                      
  
  filter {                                                                                                               
    date { match =&gt; [ "message", "YYYY-MM-DD HH:mm:ss" ] }                                                               
  }                                                                                                                      
  
  output {                                                                                                               
    stdout { codec =&gt; rubydebug }                                                                                        
  }
  </code></pre>
  
  <p>And then after typing <code>2014-02-21 12:53:41</code> I get wrong month number in <code>@timestamp</code> field:</p>
  
  <pre><code>$ java -jar logstash-1.3.3-flatjar.jar agent -f test.conf 
  2014-02-21 12:53:41
  {
         "message" =&gt; "2014-02-21 12:53:41",
        "@version" =&gt; "1",
      "@timestamp" =&gt; "2014-01-21T12:53:41.000+04:00",
            "host" =&gt; "localhost.localdomain"
  }
  </code></pre>
  
  <p>Could smb explain me what I'm doing wrong? Why the date pattern is not working as expected?</p>