Added app.json for heroku

Author: x1wins

app.json

@@ -0,0 +1,7 @@
+{
+  "name": "Tutorial Post",
+  "description": "Tutorial category, post, comment, user, rest api with rails, rspec, JWT",
+  "repository": "https://github.com/x1wins/tutorial-rails-rest-api",
+  "logo": "https://node-js-sample.herokuapp.com/node.png",
+  "keywords": ["rails", "post", "category", "comment", "forum", "bbs"]
+}