RF: Use implicit function for data inheritance
RF: Use type to cast child class
RF: Implement dummy loader for Data
RF-model: Type renamed + a few methods implemented.
RF-model: added data type
RF-model: a few more additions
RF-model: getAttributes started.
RF: Add split method for Data
RF: Fix test for data

The length of labels differ from input length
RF-model: get attributes now working.
Merge branch 'dataAbstract' of https://github.com/datalayer/model into dataAbstract
RF: Add describe method for Data
RF: Add sample variance in Data.describe
RF: Add DataRDD firsts bits
RF-model: build.sbt updated.
RF-model: new test and check for incompatible data types (inputs and labels with different sizes)
RF: Add loadCSV method
RF: Specify column label if any
RF: Specify column label if any
RF: LoadCSV for SchemaRDD