Create functional tests for all Training scenarios

[rogancarr]

As laid out in #2498 , we need scenarios to cover the Training functionality we want fully supported in V1.

Scenarios

• I can provide multiple learners and easily compare evaluation metrics between them.
• I can use an initial predictor to update/train the model for some trainers (e.g. linear learners like averaged perceptron). Specifically, start the weights for the model from the existing weights.  
• Metacomponents smartly restrict their use to compatible components.   Example: "When specifying what trainer OVA should use, a user will be able to specify any binary classifier. If they specify a regression or multi-class classifier ideally that should be a compile error."
• I can use OVA and easily add any binary classifier to it