Change tagline to use "for humans"

https://twitter.com/japaine/status/398574572259512321

Author: chadwhitacre

postgres/__init__.py

@@ -1,5 +1,4 @@
-"""The :py:mod:`postgres` Python library is a high-value abstraction over the
-`psycopg2`_ database driver.
+"""This is a PostgreSQL client library for humans.
 
 
 Installation
@@ -9,7 +8,7 @@
 
     $ pip install postgres
 
-:py:mod:`postgres` requires :py:mod:`psycopg2` version 2.5 or higher.
+:py:mod:`postgres` requires `psycopg2`_ version 2.5 or higher.
 
 We `test <https://travis-ci.org/gittip/postgres.py>`_ against Python 2.6, 2.7,
 3.2, and 3.3. We don't yet have a testing matrix for different versions of