Add lib/ansible/db_simple.py

db_simple.py is a basic db abstraction for storing results
from ansible runs via a callback.  The database has one table,
host_result, and the columns: timestamp, hostname, module (name of
module that was run, if available), result (success, failure, etc), and
data (the json result data).  While handling the data column, data
is either json encoded or decoded via json.dumps or json.loads.

I'll follow with callback_plugins/sql.py.  This is related to #2008.  Please comment on schema and I can adjust it as necessary.  :-)