Update Python Driver to use the new Prism Interface

[gartens]

This updates the Python driver to use the new Prism Interface of Polypheny. The driver is DBI 2.0 compatible except for functionality related to the type_code field of the cursor description attribute. See the tests in test_pep.py for more information.

Multi-model

The executeany method allows to use languages other than SQL. The driver can handle documents results in addition to relational results.

Breaking changes

The signature of the connect method has changed.

polypheny.connect('127.0.0.1', 20590, user='...', password='...')

becomes

polypheny.connect(('127.0.0.1', 20590), username='...', password='...', transport='plain')

If you are using the same host and user as Polypheny (and are not on Windows), you can take advantage of the new UNIX socket support of the interface and connect without any parameters at all:

polypheny.connect()

[vogti]

Thx, @gartens, for this contribution!