Initial design / flow for REST handler.

Take a look, let me know what you think.  Thus far, I implemented listKeyspaces.  
(I started on listColumnFamilies, but noticed that we don't have a handler for that yet.)
(Is someone working on that?)  

The design:  (picking up where Nate left off)
IntraHandlerRest handles the request.  (patterned after IntraHandlerJson)
It delegates to IntraHandlerRestUtils, which translates the HttpRequest into the appropriate IntraReq + IntraOp.  It then fires off an event of type "request.json", res-using the rest of the underlying infrastructure.

We may want to translate the response as well, but I haven't gotten that far yet.

I'm definitely open to critique here. 
 
I need to add unit tests.  To ensure I got the whole flow correct, I was using the curl shell scripts to test.