Revert locale

Setting the `Time.zone` in an `after_initialize` block can become a problem for people upgrading, since it's not going to be available when `config/initializers` run, and people might be relying on it.
    
An example that I noticed was with the [Chronic gem](https://github.com/mojombo/chronic), for date/time parsing. It requires us [to configure the time class to be Time.zone](https://github.com/mojombo/chronic#time-zones), and doing that in an initializer no longer worked with these changes.

Example code in `config/initializers/chronic.rb`:

```ruby
Chronic.time_class = Time.zone
```

I had to change to this to make it work with the locale change:

```ruby
Rails.configuration.after_initialize do
  Chronic.time_class = Time.zone
end
```

Even though I think it'd be good to move the locale options, I don't think this change should affect people relying on the current behavior, so it seems safer to revert now.

*I'm sending as a pull request to get some feedback from @steveklabnik and @rafaelfranca, to check if I'm not forgetting to revert anything else*.