[ffulm] turned feeds into actual submodules

This makes it easier to tweak luci
[ffulm] custom firewall rules
[ffulm] enable bridge firewalling
[ffulm] added uhttpd bindings as default packages
[ffulm] added missing firewall packages
[ffulm] addded missing firewall rule for telnet
[ffulm] added missing iptables modules for physdev target
Added build instructions in README.md.
[ffulm] added missing iptables modules for TEE target
[ffulm] make config replacements actually happen on first boot
[ffulm] updated openwrt feed
[ffulm] fixed siit checksum
[ffulm] attempt at an MTU workaround
[ffulm] fix tinc startup problems
[ffulm] disable firewall hotplug
[ffulm] start siit later
[ffulm] fix siit init script
[ffulm] better hostnames
[ffulm] added luci splash uhttpd config to uhttpd
[ffulm] add a default dns server if the box is not directly connected to the internet