Mailgun Integration 2.2.0

Notable changes:

• This version required XenForo 2.2.0

Notable changes:

• Added option to change the sender name

Notable changes:

• Improvement send emails
• Support webhooks to handle email bounce or invalid
  • https://yourdomain.com/mailgun-webhooks/spam-complaints
  • https://yourdomain.com/mailgun-webhooks/unsubscribes: Handle when user press unsubscribe in mailgun. The user will be updated to uncheck receive admin emails, email on conversations.
  • https://yourdomain.com/mailgun-webhooks/permanent-failure: Handle when mailgun cannot send email to user. The user will be mark as email bounce state