Add `script/bootstrap` to setup initial app.

When the application is deployed we need to run some initial commands to
properly setup the bundle.
Bump 'octokit' gem.
Modify Procfile to utilize binstubs and Puma config.

The Puma configuration is loaded up and then it mounts the Rack
application as it normally would.
Fix issue with load order.

Go back to loading the API version in api.rb
Fix GitHub webhook to actually accept POST.

This was an obvious mistake that I wouldn't have caught likely for a
long while.