Task Design?

[kirtsar]

What should the Task do?
my vision of working with Task object is something like:
assume that we have some data for supervised learning: X, y. X and y can be any reasonable type (X is Matrix, DataFrame, ...; y is some subtype of AbstractVector).

task = Task(data = X, target = y, goal = SomeGoal(optional args) )

where SomeGoal is something from (for example):

1. Binary(is proba = true/false)
2. Multiclass(is proba = true/false)
3. Regression(is proba = true/false)
   Based on the type of the task, the output for X_and_y should be appropriate (Continuous, discrete, ...)

[ablaom]

Sorry, closing as duplicate of #68.