DBAPI 2.0 SQL Client

* Defines an extendable DBAPI 2.0 SQL Client
* For more information on the DBAPI 2.0 standard please visit:
*     http://www.python.org/dev/peps/pep-0249
*
* BaseSQLClient:
*     Current methods:
*         connect
*         execute
*         execute_many
*         close
*
* SQLClientException

Change-Id: I872f73d7b693d3a5e301886f084d1d7df56be885
Merge "DBAPI 2.0 SQL Client"