Updates to LIPP & Future Payments

- Updated LIPP Sample code
- Updated Future Payments to have helper functions for retrieving access token
- Updated Logging Syntax to include timestamp and response json

lib/PayPal/Core/PPLoggingManager.php

@@ -70,6 +70,11 @@ class PPLoggingManager
      */
     public function __construct()
     {
+        // To suppress the warning during the date() invocation in logs, we would default the timezone to GMT.
+        if (!ini_get('date.timezone')) {
+            date_default_timezone_set('GMT');
+        }
+
         $config = PPConfigManager::getInstance()->getConfigHashmap();
 
         $this->isLoggingEnabled = (array_key_exists('log.LogEnabled', $config) && $config['log.LogEnabled'] == '1');
@@ -93,7 +98,7 @@ class PPLoggingManager
     private function log($message, $level = PPLoggingLevel::INFO)
     {
         if ($this->isLoggingEnabled && ($level <= $this->loggingLevel)) {
-            error_log($this->loggerName . ": $message\n", 3, $this->loggerFile);
+            error_log("[" .  date('d-m-Y h:i:s') . "] " . $this->loggerName . ": $message\n", 3, $this->loggerFile);
         }
     }