Dependent ability conversations

[kevinleung23]

Description: Conversation flow should have multiple abilities and slots to represent a conversation with many pieces of information required from the user. The abilities should be able to have dependencies on others abilities to represent a structured conversation flows.

Example:
Abilities:

1. Onboard user (name)
2. Departure Information (date, airport)
3. Return Information (date, airport)

Abilities 2 and 3 have a dependency on ability 1

User: I would like to book a flight from ORD to EWR.
Bot: I can certainly help you with that, but first.. what is your name?
User: Foobar
Bot: Thank you Foobar!
Bot: What date would you like to fly from ORD to EWR
User: 8/1/2018
Bot: When would you like to return?
User: 8/2/2018
Bot: Okay your round trip flight from ORD to EWR is booked! You will depart on 8/1/2018 and return on 8/2/2018.