Wrong "best_math" for Accept-* header

According to RFC: "If a parameter has a quality value of 0, then content with this parameter is `not acceptable' for the client." but unfortunately acceptparse.Accept does not conform that rule :(

Eg.:

Accept( 'Accept-Encoding', 'deflate, *;q=0' ).best_match( ['foo'] )

Returns "foo" instead of default value.

Provide a test case.

Hope it will be sufficient :-)

<pre>

1. !/usr/bin/env python
2. -*- coding: utf-8 -*- from webob.acceptparse import Accept

if 'main' == name: assert Accept('Accept-Encoding', 'bar, *;q=0').best_match( [ 'foo' ], 'baz' ) == 'baz' </pre>

I attached test case - unfortunalely putting code into comments is not a goot idea ;-)

You can wrap code like this: {{{code}}} There's a button in the comment form for that too.

Fixed in https://bitbucket.org/ianb/webob/changeset/bf59edb7224c