[pybsddb] A few small feature requests

[Yong Li]

I have a very small feature request.

1) Can __contains__ be added to bsddb.db.DB as an alias for has_key?
That would make its usage more Pythonic
2) Can iteritems be added to bsddb.db.DB? That would make it more dict-like

Sincerely,
Yong Li