Append after element unavailable

[Sardis93]

First of all, thanks for a nice lib.
But there's a small problem. I need to append signature to a specific node of the xml and there's no such possibility, so i have to extend a given class.
Could you add second parameter to the sign method and simply pass it to the sign method of XMLSecurityDSig object?

[Maks3w]

Thanks for your suggestion. Feel free to send a Pull Request with your proposal.