Replace pprint with json.dumps for --json
Replace pprint with json.dumps for --json

pprint was single-quoting things, which wasn't
making for proper json output after all.

Change-Id: I3c3fcc7d41677010593d1c8fb964d295faed45d1
Closes-Bug: #1450164

openstack/python-solumclient,stackforge/python-solumclient,stackforge/python-solumclient