Delivery Service APIs: CRUD

[mitchell852]

• [ ] get /api/$version/deliveryservices
• [ ] get /api/$version/deliveryservices/:id
• [ ] post /api/$version/deliveryservices
• [ ] put /api/$version/deliveryservices/:id
• [ ] delete /api/$version/deliveryservices/:id

[rob05c]

https://github.com/apache/incubator-trafficcontrol/pull/2124

[mitchell852]

this endpoint is addressed in #2232