Update Makefile (#78)

Sign release and make sure to tag from master

Author: stsewd

Makefile

@@ -2,9 +2,11 @@ release: clean
 	git checkout master
 	git pull origin master
 	python setup.py sdist bdist_wheel
-	python -m twine upload dist/*
+	python -m twine upload --sign --identity security@readthedocs.org dist/*
 
 tag:
+	git checkout master
+	git pull origin master
 	git tag `python -c "print(__import__('sphinx_search').__version__)"`
 	git push --tags