Avoid re-downloading resources to check whether they're finished

Otherwise, in a LocalEnsemble, all models are reloaded every time we
call predict.
Fix for local predictions sans confidence

LocalPredictiveModel.predict expects MultiModel.predict to always return
a hashmap as a prediction, and we were returning a plain JSON prediction
object when withConfidence was set to false.
New class for reading CSV files
LocalEnsembles cleanups
Fixes, cleanups and examples for local ensembles
Fix: collecting all model fields in an ensemble

Depending on how the ensemble was created, individual model fields might
not be exhaustive.
Allow predictions in LocalPredictiveModel with hashmap inputs
Fix: more robust status codes checking
Adjustments for ensemble creation timeouts in unit tests
Merge pull request #10 from jaor/master

Fixes and cleanups for local ensembles