adderall.contrib: Add two modules, for fun

This introduces adderall.contrib.cheezburger.kitty and
adderall.contrib.cheezburger.grumpy-cat. Both implement canhasᵒ, which
succeeds if we can has :cheezburger. In every other case, it succeeds if
using kitty, and fails if we're under grumpy-cat.

Signed-off-by: Gergely Nagy <algernon@balabit.hu>