Added implementation for Cassette#all_payed
Added implementation for Cassette#all_payed

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