Unknown command: 'clearsessions'
You should always use manage.py rather than django-admin.py to run any commands that depend on an existing project, as that sets up DJANGO_SETTINGS_MODULE for you.
I am using Django 1.5.1, and according to django documentation cleanup is deprecated in this django version and cleansessions should be used.
When I try using cleansessions it states unknown command. And when I type djando-admin.py help. I don't get it listed in the commands, I instead get cleanup listed.
And on using django-admin.py cleanup, I get the following error -

ImproperlyConfigured: Requested setting USE_I18N, but settings are not
  configured. You must either define the environment variable
  DJANGO_SETTINGS_MODULE or call settings.configure() before accessing
  settings.

Any Idea what is causing so.