CDAP-471

1) In standalone, now stops all components, if one fails. JIRA issue has been opened to restart runnables if they fail: https://issues.cask.co/browse/CDAP-477
2) Validate the handlers that user passes in during deploy time
3) Move construction of NettyHttpServer to constructor of ServiceHttpServer (from startup)
4) Add a small test case to test (2)
Instead of having both of these, you can have `List<HttpServiceHandler>` only. Then you change the verifyHandlers method to ```Map<String, HttpServiceSpecification> createHandlerSpecifications(List<? extends HttpServiceHandler> handlers)``` that do verification and creation of spec.