Fix printing of AS number in scion.lua (#2132)
Fix printing of AS number in scion.lua (#2132)

ASes used to only ever contain ints, hence `%d` worked. Hwoever, the
newer shortened AS notation may have AS numbers like `9:5:6`, which %d
can't be used for. Switch to %s to fix this issue.
Oncilla/scion,netsec-ethz/scion,netsec-ethz/scion,Oncilla/scion,klausman/scion,klausman/scion,klausman/scion,klausman/scion,Oncilla/scion,Oncilla/scion,klausman/scion,netsec-ethz/scion,netsec-ethz/scion