Hyperstack::I18n#t should also check non-namespaced translation

Right now `Hyperstack::I18n#t` is smart in that it uses the name-spacing to look up the translation. This works great for those, but if we're trying to look up a translation outside of that namespace it will return a missing translation. You can work around this by using `I18n.t`, which isn't that much more typing, but it would be nice to have the the included helper methods be a little smarter.