Only use color logging with a tty (#1720)
Only use color logging with a tty (#1720)


netsec-ethz/scion,netsec-ethz/scion,netsec-ethz/scion,Oncilla/scion,Oncilla/scion,Oncilla/scion,klausman/scion,Oncilla/scion,klausman/scion,netsec-ethz/scion,klausman/scion,klausman/scion,klausman/scion