redirect output of rabbitmq install (LP: #878600)

as documented in ubuntu bug bug 878600, starting the rabbitmq
daemon was keeping its output filehandle open, which caused the 'tee'
to never die, and an ssh connection to never close.

stack.sh

@@ -351,7 +351,11 @@ cp $FILES/screenrc ~/.screenrc
 
 if [[ "$ENABLED_SERVICES" =~ "rabbit" ]]; then
     # Install and start rabbitmq-server
-    sudo apt-get install -y -q rabbitmq-server
+    # the temp file is necessary due to LP: #878600
+    tfile=$(mktemp)
+    sudo apt-get install -y -q rabbitmq-server > "$tfile" 2>&1
+    cat "$tfile"
+    rm -f "$tfile"
     # change the rabbit password since the default is "guest"
     sudo rabbitmqctl change_password guest $RABBIT_PASSWORD
 fi