Add MIlestone Logic to Pot and PotFactory

[codingshot]

Problem

Currently in MVP their is no milestone logic in factory contract. We need a way for projects and round managers to evaluate milestones

User Story:

As a chef, I want to enable milestones, so that I can have rounds where we monitor the effectiveness of projects to ship.

Description

Add milestone threshold, number of milestones, and milestone evidence to potfactory and pot contract

Acceptance Criteria

• able to specify number of milestones, threshold for milestones and percent paid out up front when creating pot
• on pot factory need to be able to take in a struct of milestone evidence associated with a milestoneID linked to a round application associated with a payout
• need to be able to calculate milestone payouts
• determine whether milestone has been compelted
• allow milestones to be resubmitted if has been rejected
• allow for chefs to approve milestones

Limitations

Resources

• https://docs.potlock.io