The previous mechanism didn't seem to work and newer Rails versions have
an easier config for this now.
Also fixing all i18n errors which were now failing specs.
This fixes the following deprecation warnings
```
DEPRECATION WARNING: `config.serve_static_files` is deprecated and will be removed in Rails 5.1.
Please use `config.public_file_server.enabled = true` instead.
(called from block in <top (required)> at /home/runner/work/openfoodnetwork/openfoodnetwork/config/environments/test.rb:13)
DEPRECATION WARNING: `config.static_cache_control` is deprecated and will be removed in Rails 5.1.
Please use
`config.public_file_server.headers = { 'Cache-Control' => 'public, max-age=3600' }`
instead.
(called from block in <top (required)> at /home/runner/work/openfoodnetwork/openfoodnetwork/config/environments/test.rb:14)
```
Fixes the following deprecation warning:
```
DEPRECATION WARNING: The configuration option `config.serve_static_assets` has been renamed to `config.serve_static_files` to clarify its role (it merely enables serving everything in the `public` folder and is unrelated to the asset pipeline). The `serve_
static_assets` alias will be removed in Rails 5.0. Please migrate your configuration files accordingly. (called from block in <top (required)> at /usr/src/app/config/environments/test.rb:13)
```
Fixes several errors such as:
104) UserRegistrationsController via ajax sets user.locale from cookie on create
Failure/Error: I18n.locale = spree_current_user.andand.locale || cookies[:locale] || I18n.default_locale
I18n::InvalidLocale:
"pt" is not a valid locale
# ./app/helpers/i18n_helper.rb:14:in `set_locale'
# ./spec/controllers/user_registrations_controller_spec.rb:56:in `block (3 levels) in <top (required)>'
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.
