tweak release process

Author: alimanfoo

release.txt

@@ -1,7 +1,9 @@
+# version=x.x.x
+echo $version
+git tag -a v$version -m v$version
+git push --tags
 python setup.py build_ext --inplace
 nosetests -v
 python -m doctest README.md
-version=`tail -n1 zarr/version.py | sed -e "s/.*version[ ]=[ ]'\(.*\)'/\1/"`
-echo $version
 python setup.py register sdist
 twine upload dist/zarr-${version}.tar.gz