added info on bmi and vsi (owner field)

At the top of every python file, there are imports for external modules.

For example, this imports the SoftLayer.utils module:
https://github.com/sudorandom/softlayer-api-python-client/blob/pep8/SoftLayer/CLI/modules/nas.py#L13.

and this uses it:
https://github.com/sudorandom/softlayer-api-python-client/blob/pep8/SoftLayer/CLI/modules/nas.py#L38