Support va_list in where:, find:, and countWhere:

This removes support for whereFormat: and findWithFormat: in the
process, so upgrade your calls!

Signed-off-by: Stephen Celis <stephen@stephencelis.com>
Update CHANGELOG

Signed-off-by: Stephen Celis <stephen@stephencelis.com>
Merge pull request #81 from stephencelis/default-va-lists

Support va_list in where:, find:, and countWhere:
Update new format
Update README.md