Twilio PHP 4.0.0

• Removes counts from ListResource
• Change Services_Twilio::getRequestUri() from a static method to an instance
  method.

3.12.2

• Support PHP 5.5.
• Fix string representation issues.

Mobile

• Add support for filtering by type for IncomingPhoneNumbers.
• Add support for searching for mobile numbers for both IncomingPhoneNumbers and AvailablePhoneNumbers.