Message7227

The attached patch adds support for creating JDBC connections for driver classes that aren't 
available from the system classloader but are available in the sys classloader.

The problem: java.sql.DriverManager won't create connections for drivers that aren't loaded 
in the system classloader, making it difficult to load driver classes dynamically.

A common solution is to use a delegating driver class that can handle the dynamic driver, as 
described here: http://www.kfu.com/~nsayer/Java/dyn-jdbc.html

This patch works around that, and saves the user from using the delegation approach. It
modifies zxJDBC.connect to first attempt to use DriverManager.getConnection with a fallback 
to instantiate the driver and call connect() directly. It also attempts to load the driver
class in the system state classloader instead of the system classloader.

The patch has a null check around Py.getSystemState().getClassLoader(), but will that ever 
be null? I'm new to the jython codebase, so the state of that classloader is unclear to me.