Firewall Rules

Remove insecure accept all packets rules from gluon-mesh-batman-adv. 
Allow needed/common services on wan and client interfaces. 
This is also hotfixing gluon issue #100, but not resolving it.

The connection tracking patch is especially useful for the auto updater feature,
otherwise we will not be able to make connection through the closed firewall.
On the wan interface the per default activated masquerade will do the trick.