fix(HttpClient): let local curl set encoding based what it is built with

Previously we forced it to gzip but it's possible for a local curl:

- not to have been built with gzip
- to support additional encoding types

In most cases this won't change behavior (i.e. gzip will still be used). 

Signed-off-by: Josh <josh.t.richards@gmail.com>

lib/private/Http/Client/Client.php

@@ -85,7 +85,8 @@ class Client implements IClient {
 		}
 
 		if (!isset($options[RequestOptions::HEADERS]['Accept-Encoding'])) {
-			$options[RequestOptions::HEADERS]['Accept-Encoding'] = 'gzip';
+			// let curl populate with whatever encodings it has been built with
+			$options['curl'][CURLOPT_ACCEPT_ENCODING] = '';
 		}
 
 		// Fallback for save_to