Remove verification function which is cryptographically weak

[rkeene]

The following code updates an introduced a weakness in the verification of certificate signatures. There are no cases where we do not know the curve being used when validating a signature, but this function works around a hypothetical case by trying multiple signature verifications and returning success if any of them pass.

https://github.com/KeetaNetwork/node-rs/pull/26/changes#diff-004a1fd4441a4d4d96a30edfd022e47f5bf2de7e276f397fd1cc4f83e267bce2R742-R753

Any usage of this function would also be a bug.