Functions and scripts to generate performance plots

[elboyran]

Create functions to generate performance plots as required by issue #24 .

• [x] Function for accuracy plot generation for all models
• [x] Script (unit-test) for accuracy plot generation for all models for all data-sets
• [x] Function for generating Precision and Recall plots for all models for one class
• [x] Script (unit-test) for generating Precision and Recall plots for all models for one class for all data-sets
• [x] Function for generating Precision and Recall plots for one model for all classes
• [x] Script (unit-test) for generating Precision and Recall plots for one model for all classes for all data-sets