fix quoting in ./run.sh to handle paths with spaces

fixes #2

run.sh

@@ -8,14 +8,14 @@ while getopts "c:f" flag; do
     esac
 done
 
-if [ -z ${SIGNAL_DIR+x} ]; then
+if [ -z "${SIGNAL_DIR+x}" ]; then
     echo -e "a signal configuration directory is required. for example:\n"
     echo -e "  $ run.sh -c ~/.config/Signal/\n"
     exit 1
 fi
 
 if [ $FILTER -eq 1 ]; then
-    docker run -it -v $SIGNAL_DIR:/root/.config/Signal -v ./output:/output sigint -f config/chat_list.txt
+    docker run -it -v "$SIGNAL_DIR":/root/.config/Signal -v ./output:/output sigint -f config/chat_list.txt
 else
-    docker run -it -v $SIGNAL_DIR:/root/.config/Signal -v ./output:/output sigint
+    docker run -it -v "$SIGNAL_DIR":/root/.config/Signal -v ./output:/output sigint
 fi