os.environ reflects the shell environment, not the WSGI environment

`os.environ` is patched by the dev_appserver to be a delegating object that looks up the current request environ. As the patches on `os` are all removed by djangae when running locally (in order to enable subprocess calls), the value of `os.environ` differs between production and development environments.

This PR explicitly re-patches `os.environ` to fix this behaviour.