Problem processing the PENDING response message

[kuehne-trustable-de]

Some devices see problems processing the PENDING response message. The missing content just get's ignored and the following signer certificates of the PKCS#7 container get mis-interpreted as the created certificates. This is obviously a problem of the device but a fix in jscep seems to be a much easier way to fix the problem.

The idea is to add dummy content of the PKCS#7 container. This approach fixes our problem but I'm not sure whether all clients will interpret this structure in the intend way.

See pull request #220