CDAP-471 - Validate Service Handlers during deploy time.

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-471
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)

https://bamboo-prod.continuuity.com/browse/CDAP-DUT79
I think this would be the place where we can perform a restart upon failure (instead of propagating the specific error upwards, and performing the restart elsewhere).
So we probably don't need to send different type of exception, depending on where the restart logic will be.