using quotes when echo something
fix led permissions, thery are actually GPIO
dhcp timeout set to 10 seconds instead of 60 seconds
ref url:
http://linux.die.net/man/5/dhclient.conf
https://wiki.debian.org/NetworkConfiguration
fix random emac. This close issue #47,#63
the mac address setted in script.bin has the highest priority
if not set, we will use a temporary static mac address instead