1. Update DecisionStep so it highlights, displays Tooltip on hover, and displays Dropdown menu when clicked. 2. Create stories for DecisionStep. <img width="356" alt="Screenshot 2019-11-01 14 08 09" src="https://user-images.githubusercontent.com/5825343/68046098-6d058500-fcb1-11e9-9f3a-ea1b1be39f06.png">
