Revise localized agreements

This is a very rough draft of revising the way we're localizing the agreements after the discussion following https://github.com/mozilla/fxoss/issues/199#issuecomment-51694614. Will utilize the "Ready for Review" label when appropriate.
Personally I think the dict makes it harder to understand (as opposed to two if statements sort've like you had before) but this totally looks like it does the right thing.