Always quote qop parameter.

>According to http://tools.ietf.org/html/rfc2617#section-3.2.1 the qop
>attribute of the www-authenticate header is always enquoted even when a
>single token.

Fix #633
Merge pull request #634 from untitaker/issue633

Always quote qop parameter.
Merge branch '0.9-maintenance'

Conflicts:
	werkzeug/testsuite/wrappers.py