Import PMML directly from compressed format

[iamDecode]

Random forest and gradient boosting PMML files can easily exceed 100s of mbs in size, which takes a while to load. As the format is XML-based, its well suited for compression, and can reduce the file size many-fold. It is worth exploring whether loading the file directly from gzip or zip format improves loading speeds. Fewer disk operations are required, however the decompression will take some more cpu cycles.