make JobConfExternalConstructor call .addInputPath() on any InputFormat
class that supports it; minor refactorings
Merge branch 'master' of github.com:Microsoft-CISL/REEF into sergiym_dataloader_fix
Merge pull request #945 from Microsoft-CISL/sergiym_dataloader_fix

make JobConfExternalConstructor call .addInputPath() on any InputFormat class that supports it