Changing stream handling in action request; BC Break.

Will not drain stream and assign data when binary data was send. This reduces memory
usage and enables streaming very large files (i.e. uploading video content).

- `$request->data` may now be either received (form) data or an open
  stream handle if binary data was send.

- Automatic content decoding for streamed data is not supported anymore.

  This feature may return at a later point in a different implementation which may use
  stream wrappers to decode on-the-fly. Disabling corresponding tests.

  How this breaks BC: When streaming JSON or XML data, the data is not decoded
  automatically anymore. `$request->data` will therefore not hold an array of data
  anymore, but an open resource handle. You will need to read from the stream and decode
  manually:

  ```
  $data = Media::decode( // new
    $request->type,
    stream_get_contents($request->data)
  );
  ```

- Removing `stream` property and reusing data for holding stream.

  Semantically there is no difference between data in a stream and data in complex
  data structure i.e. an array.

  How this breaks BC: When initializing a request object manually a stream should
  now be passed under the `data` configuration option.

  ```
  $stream = fopen('php://temp', 'r');

  new Request(array('stream' => $stream)); // old
  new Request(array('data' => $stream)); // new
  ```

- Still autocloses opened stream.

- Refactoring `_init` to use autoConfig for data.

- Expanding documentation.

- Defaulting `data` property to `null`.