Add JSON-P support to Storm UI API

The recent API that is being released in Storm UI with 0.9.2 is great, but it'd be useful if the API supported an optional ?callback parameter that would provide a wrapped JSON-P response for all endpoints.

Example:

GET https://my-storm-head.cogtree.com/api/v1/cluster/summary?callback=myFunction

myFunction({"stormVersion":"0.9.2-incubating","nimbusUptime":"4m 55s","supervisors":2,"slotsTotal":32,"slotsUsed":0,"slotsFree":32,"executorsTotal":0,"tasksTotal":0});

This would allow users to write clients similar to elasticsearch-head (which I was hoping to build) where they could use a single UI to manage multiple Storm environments.

Having a JSON-P ?callback param would allow clients to get around browsers enforcing same-origin policies.

The JSON-P site has examples of valid callback parameters:

functionName({JSON});

obj.functionName({JSON});

obj["function-name"]({JSON});