More idiomatic (and slightly cleaner) Ruby in _build
_build script cleanup:

 * Fix all the wonkiness around translations and extras introduced by recent _build script updates.
 * Standardize translation order so that it's consistent everywhere.
 * Clean up pt_BR urls, redirect from all the other valid variations.
 * Suppress "translations" on the extras pages, since they don't work anyway.
 * Use clean urls for extras pages too. This is 2014. There's no need for .html.
 * Fix wonky # in titles of the generated PSR-4 stubs.
Do case-insensitive filesystems a favor and remove the old pt-BR before adding one that's pt-br :)
Update built PSR page stubs.