Error when deleting multiple tokens on logout

[Lin Hua Cheng]

On user logout, each token created is iterated and revoked.

On token revocation, it requires a valid token to be passed in the header. If the token used has already been revoked during the for..loop of the token revocation, it throws an exception.

For example:

There are token#1, token#2 and token#3 stored in session, and token#2 is stored in the auth_token of the client code. By the time the application tries to revoke token#3, token#2 has already been revoked and cannot be used to revoke token#3.

[Lin Hua Cheng (lin-hua-cheng)]

Fix proposed at: https://github.com/gabrielhurley/django_openstack_auth/pull/20

[Lin Hua Cheng (lin-hua-cheng)]

Fix merged