Add fkill cli program

Author: lukasmasuch

Dockerfile

@@ -951,6 +951,8 @@ RUN \
     fi && \
     # Activate pretty-errors
     python -m pretty_errors -u -p && \
+    # Install fkill-cli program  TODO: 30MB, remove?
+    npm install --global fkill-cli && \
     # Cleanup
     clean-layer.sh