[Http] Abstracting protocolVersion. Not forcing CurlFactory to be a singleton, but the singleton instance is available for performance.

library/Guzzle/Http/Curl/CurlFactory.php

@@ -60,22 +60,6 @@ class CurlFactory implements CurlFactoryInterface
         return self::$instance;
     }
 
-    /**
-     * Singleton constructor
-     * @codeCoverageIgnore
-     */
-    private function __construct() 
-    {
-    }
-
-    /**
-     * Singleton clone
-     * @codeCoverageIgnore
-     */
-    private function __clone() 
-    {
-    }
-
     /**
      * Get the number of connections per host
      *

library/Guzzle/Http/Message/AbstractMessage.php

@@ -31,6 +31,11 @@ abstract class AbstractMessage implements MessageInterface
      */
     protected $cacheControl = null;
 
+    /*
+     * @var string HTTP protocol version of the message
+     */
+    protected $protocolVersion = '1.1';
+
     /**
      * Get application and plugin specific parameters set on the message.  The
      * return object is a reference to the internal object.

library/Guzzle/Http/Message/Request.php

@@ -44,11 +44,6 @@ use Guzzle\Http\Url;
  */
 class Request extends AbstractMessage implements RequestInterface
 {
-    /**
-     * @var string Protocol version of the request (1.0, 1.1, etc)
-     */
-    protected $protocolVersion = '1.1';
-
     /**
      * @var Url HTTP Url
      */

library/Guzzle/Http/Message/Response.php

@@ -84,21 +84,13 @@ class Response extends AbstractMessage
      */
     protected $protocol = 'HTTP';
 
-    /*
-     * @var string HTTP protocol version
-     */
-    protected $protocolVersion = '1.1';
-
     /**
      * @var array Information about the request
      */
     protected $info = array();
 
     /**
-     * The request object associated with the response.  This value may or
-     * may not be set
-     *
-     * @var RequestInterface
+     * @var RequestInterface Request object that may or may not be set
      */
     protected $request = null;