Use URL names in place of Python paths

Use URL names in place of Python paths

Reversing by Python paths has been deprecated in Django 1.8, causes
warnings in Django 1.9 and will be removed in Django 2.0. Resolve the
warnings and prevent issues in the future by referring to URLs by name,
rather than by Python path.

https://docs.djangoproject.com/en/1.9/releases/1.8/#passing-a-dotted-path-to-reverse-and-url

Signed-off-by: Stephen Finucane <stephen.finucane@intel.com>