Ensure sig handler routine returns on shutdown, turn it off in most tests

I noticed that when running the test suite, there would be a file
server/log1.txt left. This file is created by one of the config
reload test. Running this test individually was doing the proper
cleanup. I noticed that the Signal test that was checking
that files could be rotated was causing this side effect.
It turns out that none of the config reload tests were disabling
the signal handler (NoSigs=true), and since the go routine would
be left running, running the TestSignalToReOpenLogFile() test
would interact with an already finished test.

I put a thread dump in handleSignals() to track all tests that
were causing this function to start the go routine because NoSigs
was not set to true. I fixed all those tests. At this time, there
are only 2 tests that need to start the signal handler.

I have also fixed the code so that the signal handler routine select
on a server quitCh that is closed on shutdown so that this go routine
exit and is waiting on using the grWG wait group.

server/signal.go

@@ -37,21 +37,28 @@ func (s *Server) handleSignals() {
 
 	signal.Notify(c, syscall.SIGINT, syscall.SIGUSR1, syscall.SIGHUP)
 
+	s.grWG.Add(1)
 	go func() {
-		for sig := range c {
-			s.Debugf("Trapped %q signal", sig)
-			switch sig {
-			case syscall.SIGINT:
-				s.Noticef("Server Exiting..")
-				os.Exit(0)
-			case syscall.SIGUSR1:
-				// File log re-open for rotating file logs.
-				s.ReOpenLogFile()
-			case syscall.SIGHUP:
-				// Config reload.
-				if err := s.Reload(); err != nil {
-					s.Errorf("Failed to reload server configuration: %s", err)
+		defer s.grWG.Done()
+		for {
+			select {
+			case sig := <-c:
+				s.Debugf("Trapped %q signal", sig)
+				switch sig {
+				case syscall.SIGINT:
+					s.Noticef("Server Exiting..")
+					os.Exit(0)
+				case syscall.SIGUSR1:
+					// File log re-open for rotating file logs.
+					s.ReOpenLogFile()
+				case syscall.SIGHUP:
+					// Config reload.
+					if err := s.Reload(); err != nil {
+						s.Errorf("Failed to reload server configuration: %s", err)
+					}
 				}
+			case <-s.quitCh:
+				return
 			}
 		}
 	}()