Shutdown 0 not waiting for active connection to complete

[ngoyal16]

We are trying to shutdown server with 0 and wait active connection to be terminate.

but as soon as Shutdown function get called the server is get terminated.

we should increment connWaitGroup using .Add(1) and once the connection terminate we should use .Done() function so that the connWaitGroup.wait() funciton wil be wait until the active connection(s) is closed.

[ngoyal16]

@maurice2k #2