Add to Proxy adapter all the options of the Socket adapter

sslcafile and sslverifypeername were present in the Socket adapter
but not in the Proxy adapter.

We need all the options in order to avoid PHP warnings about accessing
invalid array keys.

Author: mlocati

src/Client/Adapter/Proxy.php

@@ -31,19 +31,21 @@ class Proxy extends Socket
      * @var array
      */
     protected $config = [
+        'persistent'         => false,
         'ssltransport'       => 'ssl',
         'sslcert'            => null,
         'sslpassphrase'      => null,
         'sslverifypeer'      => true,
+        'sslcafile'          => null,
         'sslcapath'          => null,
         'sslallowselfsigned' => false,
         'sslusecontext'      => false,
+        'sslverifypeername'  => true,
         'proxy_host'         => '',
         'proxy_port'         => 8080,
         'proxy_user'         => '',
         'proxy_pass'         => '',
         'proxy_auth'         => Client::AUTH_BASIC,
-        'persistent'         => false
     ];
 
     /**