Update created? check for new API compatabiity.

The new ES API removed :ok <bool> from rest responses and instead relies on
a :status <status code>. See: https://github.com/elasticsearch/elasticsearch/issues/4310
for the corresponding ES change.

Updates to related code and and some tests.
Make boolean assertions more succinct.
Fix native tests using updated rest response functions.
Use appropriate validators for native API tests.

Included:
- A native mapping deletion should return acknowledgement. The API
supports it, and not returning the acknowledged status is not consistent
with the rest of the fns in the namespace.
- Delete duplicate code. There existed two copies of:
clojurewerkz.elastisch.native.response/created-or-acknowledged?
Merge pull request #81 from olimcc/master

Update created? check for new API compatabiity.