Not extracting all certificates from keyfile

[Hemdian]

NVPClient.RunTransaction() used to use X509Certificate2Collection.Import() to extract all certificates from a keyfile into a collection. This has been changed to now instantiate a certificate from the keyfile and add it to the collection instead. That means the collection will now only have one certificate whereas it used to have multiple. When using config.UseSignedAndEncrypted, the code will look for a merchant certificate AND a cybersource certificate ... and now fails. This bug seems to be repeated multiple times in NVPClient.cs, SoapClient.cs, and XmlClient.cs.