Use new Organization Pattern and start allowing Webhooks

[tarebyte]

This adds a few new pieces:

• Created anOrganization::Creator which helps us abstract everything that is needed for creating an organization. This will be the pattern going forward that we will be using so that our model creating isn't dependent on the API.
• We now add a webhook for every new org we create ask for all events. That way we don't have to update all of the hooks we've created.
• We now accept the ping event, I'll follow up with code from @cyhsutw's old PR's to make a way to re-request the ping event if for some reason we don't receive it.
• Add instructions for using ngrok so that devs can get webhooks from GitHub to their application.

Todo

Extract migration from PR and ship it before hand. See #798