Handle situation when I18n date.order values are strings

Rails 4 changes the `date.order` I18n setting to return strings, which
resulted in a missed lookup in POSITION, and a value like `date_i`
instead of `date_1i` for the `for` attribute on `label` elements.
Merge pull request #848 from mjankowski/master

Handle situation when I18n date.order values are strings