added support for post_status query param.  Example: get_category_posts/?slug=faq&post_status=future
Added support for category_id, category_slug, tag_id, and tag_slug as query params from any list method (get_tag_posts, get_category_posts, etc.). This allows more fine contorl over posts queries.
Merge pull request #2 from crgwbr/master

Expanded allowed parameters