Use buildpack registry URIs instead of github URLs

Author: jkutner

README.md

@@ -22,7 +22,7 @@ Create a Heroku app, set your ngrok token, and push:
 ```sh-session
 $ heroku create
 $ heroku buildpacks:add heroku/jvm
-$ heroku buildpacks:add https://github.com/jkutner/heroku-buildpack-minecraft
+$ heroku buildpacks:add jkutner/minecraft
 $ heroku config:set NGROK_API_TOKEN="xxxxx"
 $ git push heroku master
 ```

app.json

@@ -30,10 +30,10 @@
   },
   "buildpacks": [
     {
-      "url": "https://github.com/heroku/heroku-buildpack-jvm-common"
+      "url": "heroku/jvm"
     },
     {
-      "url": "https://github.com/kr/heroku-buildpack-inline.git"
+      "url": "heroku-community/inline"
     }
   ]
 }