Make naming of Error and Warning classes consistent with other NI drivers.

[marcoskirsch]

Follow what other NI Python driver bindings (daqmx and nixnet) as far as the naming of their Error and Warning clases.

See:

• https://github.com/ni/nidaqmx-python/blob/master/nidaqmx/errors.py
• https://github.com/ni/nixnet-python/blob/master/nixnet/errors.py

for reference

[Fladolcetta]

This is fixed. We need to add the specific pull request.

[texasaggie97-zz]

Fixed in #231