supply item.keywords on funcarg requests and metafunc as well

Originally reported by: **Ronny Pfannschmidt (BitBucket: [RonnyPfannschmidt](http://bitbucket.org/RonnyPfannschmidt), GitHub: [RonnyPfannschmidt](http://github.com/RonnyPfannschmidt))**

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it would ease dealing with marks

the getattr stuff i have in place is a bit unpleasant

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- Bitbucket: https://bitbucket.org/pytest-dev/pytest/issue/2
