Twilio delivery method allows Notifier to handle errors

[bibstha]

Pull Request

Summary:
This PR allows handling Twilio errors in the Notifier. This is very similar to how other DeliveryMethods do it.
eg in fcm.rb

noticed/lib/noticed/delivery_methods/fcm.rb

Lines 18 to 23 in 1514ae3

	rescue Noticed::ResponseUnsuccessful => exception
	if exception.response.code == "404" && config[:invalid_token]
	notification.instance_exec(device_token, &config[:invalid_token])
	else
	raise
	end

Description:
Twilio has very verbose errors (including error codes) that allows API callers to do follow up actions.
eg: Error code 21211 shows that the number is invalid. In this case, we can mark a phone number as invalid to prevent further calls to Twilio.

Testing:
Added a test for the added code.

Screenshots (if applicable):
Also added example in the Twilio documentation

Checklist:

• Code follows the project's coding standards
• Tests have been added or updated to cover the changes
• Documentation has been updated (if applicable)
• All existing tests pass
• Conforms to the contributing guidelines

Additional Notes:

[excid3]

Suggested change

	Twilio provides a full list of error codes that can be handled as needed. See https://www.twilio.com/docs/api/errors

[excid3]

I think this makes sense. I don't imagine you'll need to handle anything other than 4xx errors.