misc (sat.sh): exec + better stop:

- use exec to launch twistd which is specially useful in foreground mode, so signals and other stuff are handled correctly
    - sat.sh stop now wait until the backend is actually stopped before exiting (before it was just sending the signal and leaving)

src/sat.sh

@@ -9,8 +9,12 @@ kill_process() {
     if [ -f $1 ]; then
         PID=`cat $1`
         if ps -p $PID > /dev/null; then
-            echo "Terminating $2... "
+            printf  "Terminating $2... "
             kill $PID
+            while ps -p $PID > /dev/null; do
+                sleep 0.2
+            done
+            printf "OK\n"
         else
             echo "No running process of ID $PID... removing PID file"
             rm -f $1
@@ -99,4 +103,4 @@ if [ ! -d $log_dir ] ; then
     mkdir $log_dir
 fi
 
-twistd $MAIN_OPTIONS $ADDITIONAL_OPTIONS $APP_NAME_FILE
+exec twistd $MAIN_OPTIONS $ADDITIONAL_OPTIONS $APP_NAME_FILE