update travis to run both with and without requests library
update travis to run both with and without requests library

agriffis/vcrpy,graingert/vcrpy,graingert/vcrpy,yarikoptic/vcrpy,bcen/vcrpy,IvanMalison/vcrpy,ByteInternet/vcrpy,aclevy/vcrpy,poussik/vcrpy,ByteInternet/vcrpy,mgeisler/vcrpy,gwillem/vcrpy,kevin1024/vcrpy,kevin1024/vcrpy,poussik/vcrpy