Authorization Cache to use both boolean and string in configuration

- both true and 'true' will enable authorization cache

lib/PayPal/Cache/AuthorizationCache.php

@@ -85,7 +85,7 @@ abstract class AuthorizationCache
         $config = ($config && is_array($config)) ? $config : PayPalConfigManager::getInstance()->getConfigHashmap();
         if (array_key_exists("cache.enabled", $config)) {
             $value = $config['cache.enabled'];
-            return (trim($value) == 'true') ?  true : false;
+            return (trim($value) == true || trim($value) == 'true') ?  true : false;
         }
         return false;
     }

sample/bootstrap.php

@@ -77,7 +77,7 @@ function getApiContext($clientId, $clientSecret)
             'log.FileName' => '../PayPal.log',
             'log.LogLevel' => 'FINE',
             'validation.level' => 'log',
-            'cache.enabled' => 'true',
+            'cache.enabled' => true,
             // 'http.headers.PayPal-Partner-Attribution-Id' => '123123123'
         )
     );