This change enables us to host the Flask OKpy server at a non-root URL, e.g.
prefixing all the routes with `/foo`. The non-root URL host is enabled by
setting the following environment variables:

```
SCRIPT_NAME=/foo
APPLICATION_ROOT=/foo
```

Being able to host the application at a non-root URL enables use-cases such as
for example a single SSL certificate and DNS entry being used for both the OKpy
application and the AutoPY application with routing between the two
applications being done by a URL prefix.