Add dev command for local backend shell

dev.sh

@@ -114,6 +114,15 @@ runBackend() {
   esac
 }
 
+runBackendShell() {
+  echo "Running shell in the local dashboard backend environment."
+  pushd backend > /dev/null
+  source venv/bin/activate
+  env $(xargs <backend.env) bash
+  deactivate
+  popd > /dev/null
+}
+
 runFrontend() {
   echo "Running dashboard frontend locally and connecting to cluster."
   case $mode in
@@ -172,6 +181,12 @@ then
   exit 0
 fi
 
+if [ "$1" == "backend-shell" ]
+then
+    runBackendShell
+    exit 0
+fi
+
 if [ $# -eq 1 ]
 then
   mode="native"