Add additional ticket listing endpoints

From here:

http://developer.zendesk.com/documentation/rest_api/tickets.html#listing-tickets

Add these endpoints:

GET /api/v2/organizations/{organization_id}/tickets.json
GET /api/v2/users/{user_id}/tickets/requested.json
GET /api/v2/users/{user_id}/tickets/ccd.json
GET /api/v2/tickets/recent.json