Account and container info fixes and improvement.

- Fixes bug 1119282.
- Allow middleware accessing metadata of an account without having to
  store it separately in a new memcache namespace.
- Add tests for get_container_info that was previously missed.
- Add get_account_info method based on get_container_info, a function
  for other middleware to query accounts.
- Rename container_info['count'] as container_info['object_count'].

Change-Id: I43787916c7a812cb08d278edf45370521f12c912
Merge "Account and container info fixes and improvement."