ENYO-1740: allow raw-data (Buffer) as a payload

- Some web services do not support chunked encoding (HTTP streaming)
  with PUT.  Is this case, the client must set the Content-Length
  header.  The code as it was only supported a String payload, because
  Buffer.byteLength() only accepts a String as a parameter.
- New code accepts raw data. contained in a Buffer.

Enyo-DCO-1.1-Signed-off-by: Francois-Xavier KOWALSKI <francois-xavier.kowalski@hp.com>
Merge pull request #1 from enyojs/ENYO-1740

ENYO-1740: allow raw-data (Buffer) as a payload