Task: Subscription Route

[MiMiTooU]

there is a API layer so no need for actual logic, just process the params

prefix is /subscription
This shall contain serveral routes for subscription, and typing models for params

1. /
   POST for posting a subscribe request to a specific hub with a specific topic
   DELETE for unsubscribing

2. /callback
   this is for a hub to callback
   GET is for validating subscription
   POST is for the hub to post updates
   remember there may be different hub, so there could be various updates or validation coming in

3. /hub
   contains a GET for all the hubs in a list

4. /hub/{ID}
   follows restapi
   has ability to crud hubs, that is , checking a hub,adding a new hub, deleting a existing hub, editing a hub's info