Allow SMV to parse PMML models

[yw-yang]

Currently SMV ModelExec can only parse the result of SmvModel, to provide more flexibility to users who train model with other tools but want to deploy model in Atlas, can we create a separate SMV class type (e.g. SmvPmmlModelExec) for the parsing of PMML models? The extrarequires in that class would be a reference to a PMML model rather than a persisted/published output of an SmvModel.

[laneb]

Would the PMML be the output of another module or is this more like reading a raw input file and casting it as PMML?

[yw-yang]

For this ticket, it is more like reading an external pmml file which is generated by other statistical tools, e.g. python, R.