Fetch multiple pages of tags

Over at mikeal/request#1206 and mikeal/request#1207 we're trying to update the changelog using github-changes.  The issue I was running into was that only 1 page of tags is fetched (30 items by default).

This PR is an attempt to fetch all pages of tags from the GitHub API, but it's not quite working and I'm not sure why.  I left `per_page: 30` rather than setting `per_page: 100` like you'd probably want, so that you can see the failure by running this command:

```sh
bin/index.js -o mikeal -r request \
  --auth --verbose \
  --file CHANGELOG.md \
  --only-pulls --use-commit-body
```