Config heroku deployment

app.json

@@ -0,0 +1,33 @@
+{
+  "name": "HackMD",
+  "description": "Realtime collaborative markdown notes on all platforms",
+  "keywords": [
+    "Collaborative",
+    "Markdown",
+    "Notes"
+  ],
+  "website": "https://hackmd.io",
+  "repository": "https://github.com/hackmdio/hackmd",
+  "logo": "https://github.com/hackmdio/hackmd/raw/master/public/hackmd-icon-1024.png",
+  "success_url": "/",
+  "scripts": {
+    "postdeploy": "./node_modules/.bin/sequelize db:migrate"
+  },
+  "env": {
+    "BUILD_ASSETS": {
+      "description": "Our build script variable",
+      "value": "true"
+    },
+    "NPM_CONFIG_PRODUCTION": {
+      "description": "Let npm also install development build tool",
+      "value": "false"
+    },
+    "DB_TYPE": {
+      "description": "Specify database type. See sequelize available databases. Default using postgres",
+      "value": "postgres"
+    }
+  },
+  "addons": [
+    "heroku-postgresql"
+  ]
+}