Made ganetiviz views pep8 compliant, removed redundant imports.

refs #15009
Made ganetiviz urls pep8 compliant.

refs #15009
Updated ganetiviz urls to correct model imports as per new gwm layout
ganetiviz/urls.py - Relaxed the instance_hostname matching regex in to match any string
(except forward slashes)
Deleted the redundant views in ganetiviz