Product class signatureVersion default to v1

The BinaryProductHandler does not write out the signatureVersion if it is v1. When receiving binary contents that contain a signature v1, the current client version will assume that the signatureVersion is v2 and add that to the signature history. We need to change the default signatureVersion to v1 to catch this. Any signatures created with v2 will have the signatureVersion provided so this default won't affect them.

AC: Change the default signatureVersion in Product to v1