es_deactivate error in 0.7.7

[codekiln]

Currently, if you run ./manage.py es_list and you see all activated IndexVersions, and then you run ./manage.py es_deactivate myindex where myindex is the name of a formerly activated index, you will get a stack trace on all management comands after that. For example, subsequently running ./manage.py es_list gives:

[2018-10-02 14:25:17.722210]: While completing create_index, encountered exception: 
 - message: Empty value passed for a required argument 'index'. 
 - exception doc: Inappropriate argument value (of correct type). 
 - exception stack: Traceback (most recent call last):
  File "/home/ubuntu/hbx/python/src/django-elastic-migrations/django_elastic_migrations/models.py", line 326, in start_action
    result = self.perform_action(dem_index, *args, **kwargs)
  File "/home/ubuntu/hbx/python/src/django-elastic-migrations/django_elastic_migrations/models.py", line 702, in perform_action
    created = dem_index.create_if_not_in_es()
  File "/home/ubuntu/hbx/python/src/django-elastic-migrations/django_elastic_migrations/indexes.py", line 832, in create_if_not_in_es
    raise ex
  File "/home/ubuntu/hbx/python/src/django-elastic-migrations/django_elastic_migrations/indexes.py", line 826, in create_if_not_in_es
    self.connection.indices.create(index=index, body=body, **kwargs)
  File "/home/ubuntu/hbx/python/lib/python3.5/site-packages/elasticsearch/client/utils.py", line 76, in _wrapped
    return func(*args, params=params, **kwargs)
  File "/home/ubuntu/hbx/python/lib/python3.5/site-packages/elasticsearch/client/indices.py", line 86, in create
    raise ValueError("Empty value passed for a required argument 'index'.")
ValueError: Empty value passed for a required argument 'index'.

This task is to either remove es_deactivate (since it's not really a needed feature) or to fix the bug and add tests for it.