title: Elasticsearch date range query ignores month field
body: <p>I've been using Elasticsearch as my data store and I got lots of documents in it. My problem is, I figured out that Elasticsearch ignores the month part of the mapping's date field.</p>
  
  <p>Here is what I have in my index and my query, please tell me if I'm wrong:</p>
  
  <pre><code>curl -XPUT 'http://localhost:9200/tt6/' -d '{}'
  curl -XPUT 'http://localhost:9200/tt6/tweet/_mapping' -d '{"tweet" : {"properties" : {"date" : {"type" : "date", "format": "YYYY-MM-DD HH:mm:ss" }}}}'
  curl -XPUT 'http://localhost:9200/tt6/tweet/1' -d '{"date": "2014-02-14 04:00:45"}'
  
  curl -XGET 'http://localhost:9200/tt6/_search' -d '
  {
    "query": {
      "bool": {
        "must": [
          {
            "range": {
              "tweet.date": {
                "from": "2014-12-01 00:00:00",
                "to": "2014-12-30 00:00:00"
              }
            }
          }
        ],
        "must_not": [],
        "should": []
      }
    },
    "from": 0,
    "size": 10,
    "sort": [],
    "facets": {}
  }'
  </code></pre>
  
  <p>And my response is</p>
  
  <pre><code>{
    "took": 3,
    "timed_out": false,
    "_shards": {
      "total": 5,
      "successful": 5,
      "failed": 0
    },
    "hits": {
      "total": 1,
      "max_score": 1,
      "hits": [
        {
          "_index": "tt6",
          "_type": "tweet",
          "_id": "1",
          "_score": 1,
          "_source": {
            "date": "2014-02-14 04:00:45",
            "name": "test"
          }
        }
      ]
    }
  }
  </code></pre>
  
  <p>With the given date range there should be no response between the 1st of December 2014 and the 30th of December 2014, but Elasticsearch returns entries outside of the range. Why is that so?</p>