Show performance on test data bug

[agitter]

The software shows the test data option in the "Show performance on" menu in Step 2 after resuming the workflow. This option should be hidden during Step 2. The test option gives an error if trying to click Data Plot:

Traceback (most recent call last):
  File "...\ml4bio\ml4bio.py", line 1197, in plot
    self.curr_model.plot_decision_regions(option, self.canvas)
  File "...\ml4bio\model.py", line 396, in plot_decision_regions
    X = self.test_X
AttributeError: 'DecisionTree' object has no attribute 'test_X'