Add Support for Table Output

[kmader]

Many operations performing regression or classification would produce table output. It would be particularly nice to have support for tools like pyradiomics using Docker (AIM-Harvard/pyradiomics#240) rather than manually building the extension (https://github.com/Radiomics/SlicerRadiomics)

[mpslxz]

@kmader We are planning to add classification output to the gui. Also, we need to have an interactive json generator code on the website so that in input/output and other properties are unified. Once we have the generator ready to go, we will update gui, accordingly.