Load adapters after routes are reloaded.

The hook was originally implemented as part of this earlier pull request: https://github.com/phrase/phrase/pull/6

However, we found that running the engine initializer after :disable_dependency_loading caused problems for other gem engines that happen to initialize after phrase app. Specifically in our case, [handlebars_assets](https://github.com/leshill/handlebars_assets) was unable to register engines with Sprockets during asset precompilation after :disable_dependency_loading.

I verified that phrase is still compatible with the i18n_routing gem when hooking in after the :set_routes_reloader_hook instead.