Migrate from ipfw to pf
use unique name for anchor and update uninstall
do not limit rule to single interface

`on lo0` limits pow to local requests, which excluded xip.io domains.
now, `to self` limits it to local interfaces, and even leaves mapping to other interfaces, like vmnet, intact.
make it possible to install from custom source

by setting ARCHIVE_URL you can override the source of the archive on install

bump version
use 127.0.0.1 instead of localhost
Merge branch 'ipfw-to-pf' of github.com:koenpunt/pow

Conflicts:
	install.sh
	lib/templates/installer/cx.pow.firewall.plist.js
	src/templates/installer/cx.pow.firewall.plist.eco