title: empty request bodies with file upload to Node/Express from AngularJS with ng-flow
body: <p>I'm using ng-flow to upload a picture.</p>
  
  <p>I need to set my upload to content type application/json: <a href="https://stackoverflow.com/questions/9901581/node-express-request-body-empty">Node (Express) request body empty</a>
  but how?</p>
  
  <p>I'm basing my code off the sample here:</p>
  
  <p><a href="https://github.com/flowjs/flow.js/tree/master/samples/Node.js" rel="nofollow noreferrer">https://github.com/flowjs/flow.js/tree/master/samples/Node.js</a></p>
  
  <p>I'm guessing its in the header configuration, but I'm guessing.
  here is my $scope.image object:</p>
  
  <pre><code>    { 
      image:  { 
      support: true
      supportDirectory: true
      files: 
      [  { 
      flowObj:  { 
      $ref: $
       } 
      file:  { 
      webkitRelativePath: 
      lastModifiedDate:  {  } 
      name: super-phillip (1).gif
      type: image/gif
      size: 931802
       } 
      name: super-phillip (1).gif
      size: 931802
      relativePath: super-phillip (1).gif
      uniqueIdentifier: 931802-super-phillip1gif
      chunks: 
      [  ]
      paused: false
      error: true
      averageSpeed: 0
      currentSpeed: 0
      _lastProgressCallback: 1399049249446
      _prevUploadedSize: 931802
      _prevProgress: 0
       }  ]
      defaults:  { 
      chunkSize: 1048576
      forceChunkSize: false
      simultaneousUploads: 3
      singleFile: false
      fileParameterName: file
      progressCallbacksInterval: 500
      speedSmoothingFactor: 0.1
      query:  {  } 
      headers:  {  } 
      withCredentials: false
      preprocess: null
      method: multipart
      prioritizeFirstAndLastChunk: false
      target: /
      testChunks: true
      generateUniqueIdentifier: null
      maxChunkRetries: 0
      chunkRetryInterval: null
      permanentErrors: 
      [ 404, 415, 500, 501 ]
      onDropStopPropagation: false
       } 
      opts:  { 
      chunkSize: 1048576
      forceChunkSize: false
      simultaneousUploads: 1
      singleFile: true
      fileParameterName: file
      progressCallbacksInterval: 500
      speedSmoothingFactor: 0.1
      query:  { 
      $ref: $["defaults"]["query"]
       } 
      headers:  { 
      $ref: $["defaults"]["headers"]
       } 
      withCredentials: false
      preprocess: null
      method: multipart
      prioritizeFirstAndLastChunk: false
      target: ./upload
      testChunks: true
      generateUniqueIdentifier: null
      maxChunkRetries: 3
      chunkRetryInterval: 5000
      permanentErrors: 
      [ 404, 501 ]
      onDropStopPropagation: false
       } 
      events:  { 
      catchall: 
      [ null, null ]
       } 
      onDrop: null
      preventEvent: null
       } 
       } 
  </code></pre>