Fix issues with create/verify VP

The Aries library doesn't verify properly the credentials when it's parsing a presentation and therefore some invalid credentials could be given which affects the signatures inclusion - e.g. which fields are considered when making and verifying VP proof signature.

Closes #20 (closed)

added Bug ReadyForDev labels

requested review from @yordan.kinkov

assigned to @lyuben.penkovski

merged

mentioned in commit 348fc4ef

mentioned in commit 6a3cfae4