[the-overmind] Add an endpoint for user reloads

Summary:
We need some way for users who are not bad to top up their HP. Would be nice to automate this but this is an easy way to start.

Add a new /reload action. Users with less than 75 HP can reload if they have 3 or fewer dislikes in the last 24 hrs.

Test Plan: npm test

Reviewers: #bitcoin_abc, Fabien

Reviewed By: #bitcoin_abc, Fabien

Subscribers: Fabien

Differential Revision: https://reviews.bitcoinabc.org/D19334