title: $all query returning no result
body: <p>I'm trying a query of this kind on my Auction collection, the objective is to return all documents with: <code>item == 2770</code> and a <code>dump == ObjectId("5104f03a46ab64d404000000") or ObjectId("51067f4946ab644003000000") or ObjectId("5106924e46ab64c81c000000")</code>.</p>
  
  <pre><code>{
      item: 2770,
      dump: {
          $all: [
              ObjectId("5104f03a46ab64d404000000"),
              ObjectId("51067f4946ab644003000000"),
              ObjectId("5106924e46ab64c81c000000")
          ]
      }
  }
  </code></pre>
  
  <p>This query doesn't return me anything, however this one (note that I use a dump contained in the $all operator), return me a list of document. Am I ignoring something about the $all operator behavior?</p>
  
  <pre><code>{
      item: 2770,
      dump: ObjectId("5106924e46ab64c81c000000")
  }
  </code></pre>
  
  <p>Here is an example of document in my Auction collection</p>
  
  <pre><code>{
      _id: ObjectId("5106924e46ab64c81c000237"),
      auc: 1560105766,
      item: 2770,
      owner: "Ozrael",
      bid: 450000,
      buyout: 450000,
      quantity: 20,
      timeLeft: "VERY_LONG",
      dump: ObjectId("5106924e46ab64c81c000000"),
      faction: "horde",
      bidPricePerUnit: 22500,
      buyoutPricePerUnit: 22500
  }
  </code></pre>