feat: global limiter caching (octokit#22)

feat: Clustering support using Redis (octokit#20)

fix: require latest Bottleneck to avoid memory leak when creating man…

…y instances

docs(README): enabled option

feat(octokit#4): match routes with a regex

feat(octokit#8): onAbuseLimit/onRateLimit

BREAKING CHANGE: Changed `octokit.throttle.on('abuse-limit', handler)` and `'rate-limit'` to
```
const octokit = new Octokit({
  throttle: {
    onAbuseLimit: handler,
    onRateLimit: handler
  }
});
```

refactor: make options() private, optimize retries (octokit#6)