Red hot hack to work around #1053

We can't monkey-patch balanced-python because balanced.http_client is
the module we need to patch, and the balanced.http_client attribute is
overriden in balanced/__init__.py to be an instance of balanced
.http_client.HTTPClient. This commit makes the change we need in our
vendor/ copy of balanced...tar.gz (eep!).
Bump version to 9.1.4
Bump version to 9.1.4-dev