* Firewall: add an option to allow extra firewall rules to be added.
* Firewall: add an option to allow extra firewall rules to be added.

* Firewall: change the policy of the INPUT chain back to ACCEPT to
  prevent a lockup when the Nix store is mounted over the network
  (i.e. in our VM tests).  This is because as soon as the policy is
  set to DROP, the iptables modules that enable access to the network
  filesystem cannot be acccessed anymore.


git-svn-id: 71c8032c709790ec749031c4215f8515ac00dc5a@26274 70bd8c7a-acb8-0310-9f0d-9cc1c95dcdbb

bnordgren/nixos,bnordgren/nixos,bnordgren/nixos,bnordgren/nixos,bnordgren/nixos