Validation error message reads wrong for password and password confirmation mismatch

[npras]

When Password and Password Confirmation is not the same, the validation error message reads like this:

"Validation failed: Password confirmation password confirmation does not match".

It reads wrong.

So, to fix this, the error is added on the ':base' key instead of the ':password_confirmation' key of the error object. Now it would read:

"Validation failed: password and password confirmation do not match"

[npras]

Tests are not affected by this change.

[mcordell]

Looks good, thank you!

[npras]

Thanks for merging!