Added bash shell option in piston script

piston

@@ -23,6 +23,7 @@ case $1 in
         echo " start                          Starts piston"
         echo " stop                           Stops piston"
         echo " restart                        Restarts piston"
+        echo " bash                           Opens a bash shell for the piston_api container"
         echo
         echo " update                         Fetches and applies latest updates"
         echo
@@ -51,6 +52,7 @@ case $1 in
     restart) docker_compose restart ;;
     start) docker_compose up -d ;;
     stop) docker_compose down ;;
+    bash) docker_compose exec api /bin/bash ;;
 
     update)
         git pull