Count emoji responses to determine which contributions are valuable

[c-lliope]

A potential solution to #3.

Right now osbot treats all contributions of a given type as if they provide equal value, but that is not the case in real life. Comments that only contain "me too!" should not be considered of equal value to comments that give a detailed bug report or implementation suggestion.

One way to judge the value of contributions is by the number of 👍 emoji responses to the contribution, vs the number of 👎 emoji responses.

[c-lliope]

Currently, accessing emoji reactions for a comment is only available to developers through the preview API: https://developer.github.com/v3/reactions/

[c-lliope]

Looks like they're working to add it to Octokit: octokit/octokit.rb#760