Support UTF8 in quasiquoted YAML

Hi!  This tiny patch enables the Groundhog quasiquoter to work with (some?) Haskell and database identifiers that contain non-ASCII characters.  The quasiquoter input is assumed to be UTF-8.

I’ve only tested this with rather simple names using accented latin characters like «á», and it works for both Haskell and doublequoted PostgreSQL identifiers.