make rejoin-stack.sh keep the same service tags

Currently rejoin-stack.sh can not keep the same screen service tags
as the first you deploy openstack due to that the stack-screenrc lack
proper command to configure screen's hardstatus. just delete the old
stack-screenrc so that function screen_rc can write proper initialize
command into stack-screenrc.

fix bug 1182597

Change-Id: I4cb4c6ded93a5c7b0bd39d65a754ddf86553463d
diff --git a/rejoin-stack.sh b/rejoin-stack.sh
index 65ba721..30b7bab 100755
--- a/rejoin-stack.sh
+++ b/rejoin-stack.sh
@@ -17,7 +17,7 @@
         echo "Attaching to already started screen session.."
         exec screen -r stack
     fi
-    exec screen -c $TOP_DIR/stack-screenrc -S $SCREEN_NAME
+    exec screen -c $TOP_DIR/stack-screenrc
 fi
 
 echo "Couldn't find $TOP_DIR/stack-screenrc file; have you run stack.sh yet?"