Make namespace deletion asynchronous

Instead of deleting a namespace synchronously as before, we now mark the namespace for deletion, disable it, and rename it. A worker then comes along and deletes the namespace in the background. This results in a *significantly* better user experience, as the namespace deletion operation now "completes" in under a second, where before it could take 10s of minutes at the worse.

Fixes https://jira.coreos.com/browse/QUAY-838

tools/deleteaccount.py

@@ -1,52 +0,0 @@
-import logging
-import sys
-
-from app import app
-from data import model
-from data.database import Repository, User
-
-logger = logging.getLogger(__name__)
-
-
-def delete_summary(username):
-  found = User.get(User.username == username)
-  dependencies = found.dependencies(search_nullable=False)
-  counts = {}
-  for expression, field in dependencies:
-    use_count = field.model_class.select().where(expression).count()
-    if use_count > 0:
-      counts[field.model_class.__name__] = use_count
-
-  return counts
-
-
-def delete_username(username):
-  # First delete the repositories owned by this user
-  found = User.get(User.username == username)
-  for repository in list(Repository.select().where(Repository.namespace_user == found)):
-    print 'Deleting repository: {0}/{1}'.format(found.username, repository.name)
-    model.repository.purge_repository(found.username, repository.name)
-
-  # Now recursively delete user, which will clean up all non-nullable referencing fields
-  print 'Deleting user: {0}'.format(username)
-  found.delete_instance(recursive=True)
-
-
-if __name__ == '__main__':
-  logging.basicConfig(level=logging.DEBUG)
-
-  summary = delete_summary(sys.argv[1]).items()
-
-  if summary:
-    print 'Will delete:'
-    for model_name, count in summary:
-      print '{0}: {1}'.format(model_name, count)
-  else:
-    print 'Nothing references user.'
-
-  print 'Delete? [y/n]'
-  delete_yn = raw_input().lower().strip()
-  if delete_yn == 'y':
-    delete_username(sys.argv[1])
-  else:
-    print 'Aborted!'