added tests for set_hdr, set_payload
added tests for set_hdr, set_payload

dmpiergiacomo/scion,dmpiergiacomo/scion,Oncilla/scion,FR4NK-W/osourced-scion,FR4NK-W/osourced-scion,dmpiergiacomo/scion,klausman/scion,klausman/scion,netsec-ethz/scion,FR4NK-W/osourced-scion,netsec-ethz/scion,Oncilla/scion,klausman/scion,dmpiergiacomo/scion,netsec-ethz/scion,FR4NK-W/osourced-scion,dmpiergiacomo/scion,netsec-ethz/scion,FR4NK-W/osourced-scion,klausman/scion,dmpiergiacomo/scion,klausman/scion,Oncilla/scion,Oncilla/scion