Refactored labels, can now add new repos

This allows you to add new repos for hubstats to watch by adding repos to the octokit.yml file. It also allows you to change the webhook endpoint with a rake task.

Rollback Plan
-------------
* To roll back this change, revert the merge with: `git revert -m 1 MERGE_SHA` and perform another deploy.

URLs
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https://sportngin.atlassian.net/browse/IS-1782

QA Plan
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> Fill in scenarios below. Review [QA Best Practices](https://source.sportngin.com/page/show/1227795-qa-best-practices).

#### Happy Path Scenarios
* Add a new repo to your octokit file, run hubstats:update to get info on the new repo.