Add more flexible parameters in connection string

[Tianoklein]

Hello,
At present, NZPY lacks the capability to modify certain parameters within the connection string, unlike other libraries.
For instance:
JAYDEBEAPI was able to add more parameters in connection string like:
connection_string='jdbc:netezza://'+dsn_hostname+':'+dsn_port+'/'+dsn_database +';loglevel=2;logdirpath=/trace/;loginTimeout=3600'

This could be usefull to prevent some issues like:

1. Trace the connection between client and server.
2. Edit default parameters to prevent the errors like:
   a) TypeError: ('communication error', TimeoutError(110, 'Connection timed out'))
   b ) TypeError: An error occurred while calling o125.save. : org.netezza.error.NzSQLException: Connection timed out (Connection timed out) at ...
3. Be connection string more flexible.

Thanks!