no earmuffs on default-data-readers
Fixing set equality.

The following:

(= #{-1} #{(Integer. -1)})

was broken due to a bug in set equality. APersistentMap deals with
things the proper way this patch mirrors the implementation direction
of it by supplying different methods for equals and equiv.

Signed-off-by: Aaron Bedra <aaron@aaronbedra.com>
Signed-off-by: Rich Hickey <richhickey@gmail.com>