TomMonks/forecast-tools: v0.1.3

Cross validation functions. In particular rolling forecast origin, sliding window and cross_validation_score Unit tests in tests/test_model_selection.py

Mean absolute scaled error. An initial implementation of it. This doesn't yet work with the cross validation code due to the difference in function signature. Propose best way around it is to create a decorator function. Unit tests in test/test_metrics.py

improved docstrings and updated cross_validation notebook.