i18n double-curly brace deprecation

Hey Mathias,

I pushed a patch to the README, but didn't run the tests b/c the gem isn't using Bundler and "rake spec" doesn't work out of the box.

You'll probably have a failing spec on breadcrumbs_helper_spec line 58:

    I18n.backend.store_translations(:en, {:breadcrumbs => {:profile => "Your Profile - {{login}}"}})

It should probably be:

    I18n.backend.store_translations(:en, {:breadcrumbs => {:profile => "Your Profile - %{login}"}})

Hope that helps!

Shay