title: Mongoose find returns document instead of specific object in array
body: <p>When I try to find specific object in array using find({query}) I always get all elements from array. 
  Activities array stores activities (it would be a thousands of them) as you can see in the following snippet:</p>
  
  <p>This is my collection:</p>
  
  <pre><code>{
      "_id" : ObjectId("58407140755324d04db2ce95"),
      "owner" : 103429326776572,
      "activities" : [
              {
                      "name" : "test1",
                      "startTime" : ISODate("2016-08-11T17:41:54Z"),
                      "type" : "te1",
                      "lat" : 1,
                      "lon" : 1,
                      "creator" : 126212904493088,
                      "coverPhoto" : {
                              "name" : "test1",
                              "path" : "c:\\Users\\Francis\\Desktop\\dusk\\public\\coverPhotos\\SJ9tpP6Mx.jpg"
                      },
                      "identifier" : "H1g9F6vpGl",
                      "users" : [
                              1,
                              2,
                              3
                      ],
                      "hashTags" : [
                              "some",
                              "hashtags"
                      ]
              },
              {
                      "name" : "test2",
                      "startTime" : ISODate("2016-08-11T17:41:53Z"),
                      "type" : "te2",
                      "lat" : 1,
                      "lon" : 1,
                      "creator" : 103312904493090,
                      "coverPhoto" : {
                              "name" : "test2",
                              "path" : "c:\\Users\\Francis\\Desktop\\dusk\\public\\coverPhotos\\Hy8qpvafe.jpg"
                      },
                      "identifier" : "rJlU5TvpMx",
                      "users" : [
                              1,
                              2,
                              3
                      ],
                      "hashTags" : [
                              "some",
                              "hashtags"
                      ]
              }
      ]
  </code></pre>
  
  <p>}</p>
  
  <p>I need to get for example an activity that has specific identifier.
  I tried to use queries like:</p>
  
  <p>1) db.myCollection.find({'activities.identifier' : "rJlU5TvpMx"})</p>
  
  <p>2) db.myCollection.find({'activities' : { $elemMatch : { "identifier" : "rJlU5TvpMx", "creator" : 103312904493090 } }) </p>
  
  <p>And all combinations with '' or "" signs</p>
  
  <p>I found above queries at mongodb docs in equal documents schema as mine is.</p>
  
  <p>Can you tell me what am I doing wrong ?</p>