Add one more class of user that sits between administrators and authors.

[FlickerSoul]

Is your improvement request related to a problem? Please describe.
The current system allows users to register as an administrator. However, a system admin should only be registered through CLI or it's going to be a potential security issue.

Describe the solution you'd like
The new class can be named as managers. The users belonging to this class can edit/create/delete any posts but cannot touch user records whereas administrators can edit user records. Authors/Translators can create new posts, and modify/delete their own posts. Visitors get no access to control panels. Consider using Django's permission system to do so.