Sort keys when writing JSON in `create_config.py`
Sort keys when writing JSON in `create_config.py`

Keeping the order of `config.json` consistent from one run to the next helps to
avoid unnecessary `grunt` builds. Fixes #99

kobotoolbox/enketo-express,onaio/enketo-express,kobotoolbox/enketo-express,OpenClinica/enketo-express-oc,kobotoolbox/enketo-express,OpenClinica/enketo-express-oc,OpenClinica/enketo-express-oc,onaio/enketo-express,enketo/enketo-express,enketo/enketo-express,kobotoolbox/enketo-express,onaio/enketo-express,enketo/enketo-express