code: function _gpfStringFromStream (readableStream) {
      var iWritableString = new _GpfStreamWritableString(),
          iReadableStream = _gpfStreamQueryReadable(readableStream);
      return iReadableStream.read(iWritableString)
          .then(function () {
              return iWritableString.toString();
          });
  }
docs: /*global _GpfStreamWritableString gpf.stream.WritableString /*global _gpfStreamQueryReadable Get an IReadableStream or fail if not implemented /*exported _gpfStringFromStream Read the stream /*#endif 
  Read the stream
  
  @param {gpf.interfaces.IReadableStream} readableStream stream to read content from
  @return {Promise<String>} Resolved when the stream has been read
  @since 0.2.1