Mime type param on Request::body no longer sets expects

As pointed out in Issue #119, setting expects here may produce unexpected results.

src/Httpful/Request.php

@@ -322,12 +322,11 @@ public function authenticateWithCert($cert, $key, $passphrase = null, $encoding
  * Set the body of the request
  * @return Request this
  * @param mixed $payload
- * @param string $mimeType currently, sets the sends AND expects mime type although this
- * behavior may change in the next minor release (as it is a potential breaking change).
+ * @param string $mimeType sets the content type for the request (no longer additionally sets "expects")
  */
  public function body($payload, $mimeType = null)
  {
- $this->mime($mimeType);
+ $this->contentType($mimeType);
  $this->payload = $payload;
  // Iserntentially don't call _serializePayload yet. Wait until
  // we actually send off the request to convert payload to string.