New test case: createprinter5.

Set and examine the Driver property.
Manager.CreatePrinter's options parameter now takes 'driver' string.

Now createprinter5 test passes.
New test case: updatedriver1.

Creates a printer and calls Printer.UpdateDriver with driver-name set.

Expected to fail as Printer.UpdateDriver is not yet implemented.
Implement Printer.UpdateDriver when driver-name is specified (#30).

Now updatedriver1 test-case passes.