neutron port-list -f csv outputs poorly formatted
JSON strings

After the change, the attached subnets are displayed
as a list of dictionaries in one line only for csv
option.
It does not modify the output for tabular format.

Closes-Bug: #1263551

Change-Id: Ia34062562f0471bc926f9fc0bbed2d5dc4352dc0
Merge "neutron port-list -f csv outputs poorly formatted JSON strings"