title: Cant create 2dsphere index in mongoDB
body: <p>When I try to create 2dsphere index in mongoDB i get this error msg:</p>
  
  <pre><code>&gt; db.mahalle.createIndex({geometry:"2dsphere"})
  {
          "createdCollectionAutomatically" : false,
          "numIndexesBefore" : 1,
          "errmsg" : "exception: Can't extract geo keys: { _id: ObjectId('55b4e025a6ef7e9c50ae79cd'), type: \"Feature\", p
  roperties: { ADI: \"Çelemli\", ILADI: \"Adana\", ILCEADI: \"Yüre?ir\", BUCAKADI: \"Merkez\", KOYADI: \"Çelemli\", ILKOD:
   1 }, geometry: { type: \"Polygon\", coordinates: [ [ [ 35.624498, 36.849395 ], [ 35.649357, 36.876937 ], [ 35.657724, 3
  6.879572 ], [ 35.663334, 36.873718 ], [ 35.668063, 36.875857 ], [ 35.671228, 36.87511 ], [ 35.676613, 36.872193 ], [ 35.
  676789, 36.86627 ], [ 35.681188, 36.865075 ], [ 35.683002, 36.864582 ], [ 35.685911, 36.858289 ], [ 35.690937, 36.856315
   ], [ 35.698809, 36.857084 ], [ 35.70811, 36.84059 ], [ 35.703934, 36.838901 ], [ 35.669599, 36.82501 ], [ 35.65748, 36.
  820107 ], [ 35.63049, 36.809188 ], [ 35.639549, 36.812853 ], [ 35.625102, 36.834434 ], [ 35.624498, 36.849395 ] ] ] } }
   Loop is not valid: [ [ 35.624498, 36.849395 ], [ 35.649357, 36.876937 ], [ 35.657724, 36.879572 ], [ 35.663334, 36.8737
  18 ], [ 35.668063, 36.875857 ], [ 35.671228, 36.87511 ], [ 35.676613, 36.872193 ], [ 35.676789, 36.86627 ], [ 35.681188,
   36.865075 ], [ 35.683002, 36.864582 ], [ 35.685911, 36.858289 ], [ 35.690937, 36.856315 ], [ 35.698809, 36.857084 ], [
  35.70811, 36.84059 ], [ 35.703934, 36.838901 ], [ 35.669599, 36.82501 ], [ 35.65748, 36.820107 ], [ 35.63049, 36.809188
  ], [ 35.639549, 36.812853 ], [ 35.625102, 36.834434 ], [ 35.624498, 36.849395 ] ] Edges 16 and 18 cross. Edge locations
  in degrees: [35.6574800, 36.8201070]-[35.6304900, 36.8091880] and [35.6395490, 36.8128530]-[35.6251020, 36.8344340]",
          "code" : 16755,
          "ok" : 0
  }
  &gt;
  </code></pre>
  
  <p>collection data looks like this:</p>
  
  <pre><code>&gt; db.mahalle.findOne()
  {
          "_id" : ObjectId("55b4e025a6ef7e9c50ae792f"),
          "type" : "Feature",
          "properties" : {
                  "KOYADI" : "Ömerli",
                  "ILKOD" : 1,
                  "ADI" : "Ömerli",
                  "ILADI" : "Adana",
                  "ILCEADI" : "Pozanty",
                  "BUCAKADI" : "Merkez"
          },
          "geometry" : {
                  "type" : "Polygon",
                  "coordinates" : [
                          [
                                  [
                                          34.840791,
                                          37.516416
                                  ],
                                  [
                                          34.843066,
                                          37.525614
                                  ],
                                  [
                                          34.847284,
                                          37.545556
                                  ],
                                  [
                                          34.849961,
                                          37.602446
                                  ],
                                  [
                                          34.892618,
                                          37.570159
                                  ],
                                  [
                                          34.8991,
                                          37.559108
                                  ],
                                  [
                                          34.902859,
                                          37.545415
                                  ],
                                  [
                                          34.887897,
                                          37.508253
                                  ],
                                  [
                                          34.843046,
                                          37.489936
                                  ],
                                  [
                                          34.842049,
                                          37.501638
                                  ],
                                  [
                                          34.840791,
                                          37.516416
                                  ]
                          ]
                  ]
          }
  }
  </code></pre>
  
  <p>I have to create 2dsphere index in order to search coordinate in Polygonal areas. How can i fix this? Thanks</p>