Model parameters not preserved through serialization

[andrewdalpino]

Hi @ianbarber

Thank you for your great work - php-svm been seeing good use in Rubix ML so far

An issue came up where the SVM model parameters are not getting serialized using either our Native or Binary (igbinary under the hood) serializers

Refer here RubixML/ML#27

I understand the extension makes use of its own persisting mechanism but it would be great if we could get it to work with the Rubix system

I figured I would come to you for some advice

Thank you