Keep it clean: no more -1 status

Title tells all :) I think we must remove the status=-1 feature so that this module does not violate the Drupal core behavior.

Current, an entity can have 4 status: allow, pending, hidden, remove. Thus we convert the last two into:
- For comments: moderated mode
- For nodes: unpublished. Node author can publish it again, so we need the fifth status: republished.

This feature will change Abuse behavior, so it is in the 2.x branch.