Use more robust and explicit file path
Switch to string and fix formatting

I18n is happy with either strings or symbols.
Use the provided "interaction" helper
Use array of strings instead of symbols

I18n doesn't care, so we shouldn't. I would use the `%i(...)` syntax,
but it's not supported in Ruby 1.9.x. So `%w(...)` is the winner!
Define self.name instead of self.model_name

See e333ffab60436d1b0e718d2d48f7463f6fafb78a for rationale.