[refactor] Remove "0002_default_permissions" migration

[pandafy]

0002_default_permissions migration add permissions to the groups for the Notification model. But since we are using notification widget to display the notifications and filters notifications based on the recipient parameter, we can remove this migration file.

Otherwise, we can make the notification widget evaluates permissions for the user.(I don't think it makes much sense.)

This issue requires investigation for any adverse effect that could arise from removing the migration file.

This issue is NOT a priority for now and is open for discussion.

NOTE: Considerations about effects on existing installations should be made before making any changes in migration history. Probably we will have to roll out this one in two separate releases.

[nemesifier]

We convened that we can close this. Let's leave it how it is and in the future if we feel the need to remove, we'll reopen this.