Fix django.conf.urls.defaults imports

These imports aren't available in Django 1.6. We need to use
django.conf.urls instead.

Partially-implements blueprint django-1point6

Change-Id: I692439a76de4fe5abff9ab9395bad5c10f1cdbba
Add logging configuration for iso8601 module

iso8601 module outputs log messages but it is not useful for users,
so this commit assigns null log handler to iso8601 module.
This change suppresses iso8601 log messages during unit tests.

Also moves openstack_dashboard related logging config for unit test
from horizon to openstack_dashboard.

Change-Id: I01cf12688118e2137382b8dc7a050b3587749354
Closes-Bug: #1250554
Merge "Fix django.conf.urls.defaults imports"