Why:
* Starting the environment, even with just `bundle exec rake`, results
in the following error:
```sh
Value assigned to config.time_zone not recognized.Run "rake -D time"
for a list of tasks for finding appropriate time zone names.
```
This change addresses the issue by:
* Adding the time zone setting to environment specific configurations,
defaulting to UTC in development, and using Melbourne in tests.
Since `en` is considered as the main fallback for all locales
ensure that it is present in all environments.
Note: Setting `config.i18n.fallbacks` to `true` means use the default locale
which means that if a particular instance is not using an `en` based locale
(the parent `en` locale is automatically derived as a fallback) then `en` will
not be available as a fallback.
