Surface `karma' via GraphQL API

[jcorrado]

ref: #70

[devth]

@jcorrado lgtm - is this ready or is there remaining work?

[jcorrado]

@devth I was planning to add some of the karma reporting aggregates we discussed, before calling this PR good to go. That being said, if you wanted to merge this tiny bit in to get something up in GQL, that's fine with me - I can cut another branch to work on the aggregates. Your call, please.

[devth]

I'm fine waiting. Just wanted to make sure you weren't blocked on me reviewing/merging.

[jcorrado]

Back to you for review, @devth.

[devth]

💯 just one tiny comment. Looking fwd to modeling users!

[jcorrado]

For future reference:

~/projects/yetibot/yetibot.core karma-in-graphql-api
❯ curl -s 'http://localhost:3003/graphql' \
     -H 'Accept: application/json' \
     --data 'query={karmas{user_id, score}}' \
     --compressed | jq .
{
  "data": {
    "karmas": [
      {
        "user_id": "@U3CTLM3DX",
        "score": 2
      },
      {
        "user_id": "jung",
        "score": 1
      }
    ]
  }
}