admin: Remove admin modifications

Remove modifications from webproject and astakos.
admin: Use a different function to get user quotas

Instead of defining our own, we can use the `list_user_quotas` function
of im.quotas. The only difference that this function has is that it
expects a list of users. In our case, we just create a list of one
item.
Merge branch 'feature-admin-quotas' into feature-admin
admin: Recognize Django "auth" app in router

The "Group" model comes from the auth app of Django. Add this to the
list of apps that will be handled by the 'astakos' db.
admin: Remove admin modifications

Remove modifications from webproject and astakos.
admin: Use a different function to get user quotas

Instead of defining our own, we can use the `list_user_quotas` function
of im.quotas. The only difference that this function has is that it
expects a list of users. In our case, we just create a list of one
item.
Merge branch 'feature-admin-router' into feature-admin
admin: Add more apps in admin router
admin: Omit activation url for non-local users

Currently, astakos fails when we try to get the activation url for a non
local user. Moreover, we have no reason to show that information, so we
can safely omit it for these users.
admin: Do not fetch outdated IPs

When finding an IP in the IP log, do not try to get its model, since it
might be deleted.
admin: Do not get model of IP from IP log

The IP may have been destroyed in the meantime.
admin: Show IP details URL only when it exists

Show the IP address as hyperlink only when that address has not been
destroyed.
Merge branch 'feature-admin-fix-demo' into feature-admin
admin: Minor error in when excluding deleted items
admin: Limit IP log lines in details

Enforce the limit for associated items for IP logs too.
Merge branch 'feature-admin-fix-demo' into feature-admin
admin-ui: Fix minor bug
admin-ui: Remove unused js files
admin-ui: Minor style fixes
Merge branch 'feature-admin-ui-demo' into feature-admin