doc: added guide for setting up NAT gateway

Guide courtesy of http://hyperboria.name/gateway
reamde: relative link to NAT guide
doc: made links to other docs relative
doc: factored non-root setup into separate file
doc: factored OpenIndiana install into file
doc: factored network service check into file
readme: moved advanced config section to bottom
readme: made network svcs check a step
doc: added disabling IPv6 listening for lighttpd
merged #293
Fixed bug in Admin Logger
Assume by default that nodes are version 1 and improve logging.