Add make shell to open a Python shell

Signed-off-by: Ben Firshman <[email protected]>

Author: bfirsh

Makefile

@@ -75,3 +75,7 @@ flake8: build
 .PHONY: docs
 docs: build-docs
 	docker run -v `pwd`/docs:/home/docker-py/docs/ -p 8000:8000 docker-py-docs mkdocs serve -a 0.0.0.0:8000
+
+.PHONY: shell
+shell: build
+	docker run -it -v /var/run/docker.sock:/var/run/docker.sock docker-py python