Forecast integration MVP

[epicalex]

Aim
To post Forecast assignments to a Slack user.

Requirements
Extend the existing Harvest integration to link with the (non-public) Forecast API.

https://github.com/inlight-media/node-forecast-api

• Map Slack user to Forecast user
  • Check if Forecast ID === Harvest ID and reuse if already configured
• Post assignments to Slack user at a configurable time every day.

Message format:

Your bookings for today:

• Duration - Client Name - Project Name
• Duration - Client Name - Project Name