HUE-8382 [core] fix django-axes 2.2.0 breaks with error field attempt_time can not be null
As per Django Doc : https://docs.djangoproject.com/en/1.11/ref/models/fields/#datefield
The difference between auto_now and auto_now_add options is: "auto_now" set the field to now every time the object is saved.
At https://github.com/cloudera/hue/blob/master/desktop/core/ext-py/django-axes-2.2.0/axes/decorators.py#L415
By changing https://github.com/cloudera/hue/blob/master/desktop/core/ext-py/django-axes-2.2.0/axes/models.py#L41 to "auto_now" fixes.
Tested:
Tested on SLES where it is failing.