Create generalised model which autodetects model type

[iamDecode]

I think the most common use case for this library would be to quickly load a PMML model file with minimal further configuration. This is currently not possible as it is required to choose which type of model you are running, and instantiate that model. To make the process easier, it would be great to have a PMMLBaseEstimator.autoDetect(pmml) method which runs some checks in order to determine if a model is supported, and if so return the parsed model in one call.