Add i18n support, some code cleanup

[sekrett]

Hi!

Now it supports i18n translations. I also removed some lines, but all tests pass.

---

This change is 

[sekrett]

Here is an i18n example:

ru:
  activerecord:
    errors:
      models:
        page:
          attributes:
            from_email:
              invalid_email: "некорректный e-mail"

I don't know, why do I have to write translation for every model I have, but it works the same way on validates_as_email_address and validates_email_format_of.

[kritik]

If you update code I'll merge your request. Anyway thanks!