Created AI interface

Modified fi_play human so that all choices are made with the getChoice method. All other methods pass parameters that are not used on the human side but when running AI it passes these onto the new AI class where a decision is made.

 - Created fi_ai which will contain the logic for decision making
 - the AI class currently just makes a choice blindly in order to test the codes functionality
 - Modifying human_agent to work with both humans and AI reduces code duplication and keeps the AI_agent class simple.