Do not fail on undefined client options properties.

lib/Predis/ClientOptions.php

@@ -56,6 +56,9 @@ class ClientOptions {
 
     public function __get($option) {
         if (!isset($this->_options[$option])) {
+            if (!isset($this->_handlers[$option])) {
+                return null;
+            }
             $handler = $this->_handlers[$option];
             $this->_options[$option] = $handler->getDefault();
         }

lib/Predis/ConnectionParameters.php

@@ -57,14 +57,14 @@ class ConnectionParameters {
         return self::$_sharedOptions;
     }
 
-    public static function define($name, Options\IOption $option) {
+    public static function define($parameter, Options\IOption $handler) {
         self::getSharedOptions();
-        self::$_sharedOptions[$name] = $option;
+        self::$_sharedOptions[$parameter] = $handler;
     }
 
-    public static function undefine($name) {
+    public static function undefine($parameter) {
         self::getSharedOptions();
-        unset(self::$_sharedOptions[$name]);
+        unset(self::$_sharedOptions[$parameter]);
     }
 
     protected function parseURI($uri) {