[ttnctl] Add ttnctl devices info command
[ttnctl] Add ttnctl devices info command

Also cleaned up tables in 'ttnctl devices'

Resolves #131

LoRaWanSoFa/ttn,LoRaWanSoFa/ttn,jvanmalder/ttn,mgranberry/ttn,TheThingsNetwork/ttn,TheThingsNetwork/ttn,mgranberry/ttn,TheThingsNetwork/ttn,jvanmalder/ttn,jvanmalder/ttn,mgranberry/ttn