CDAP-663 Implemented healthcheck for router and auth-server.

The PR enables health check for router and auth servers independent of downstream services.  
Let's not add an arbitrary sleep. Would be good to have a code snippet like
```java
int attempt = 0;
while (++attempt < 10){
  if(server.isRunning()) {
    break;
  }
  Timeunit.Sleep(1);
}
if (!server.isRunning()){
  throw RuntimeException("Service is not running after 10 seconds");
}
````