Uses github.com/galenchurch/gobone for (beagleboard local) sysfs interactions

POST <beagle-bone-ip-addr>:9000/led/:led

The beaglebone black has (4) user leds: { "usr0", "usr1", "usr2", "usr3" }

a json doc with state with the state must also be passed. Possible states are: { "on", "off" }

example:

curl -X POST 192.168.0.12:9000/led/usr3 \
        -H "Content-Type: application/json" \
        -d '{"state":"on"}'

will turn usr3 led on

$ GOARM=7 GOARCH=arm GOOS=linux go build