164796899-feature: pagination support for articles

- add app.json for heroku build

[Delivers #164796899]

app.json

@@ -0,0 +1,58 @@
+{
+  "name": "cosmos-ah-backend",
+  "description": "",
+  "scripts": {},
+  "env": {
+    "BASE_URL": {
+      "required": true
+    },
+    "FACEBOOK_APP_SECRET": {
+      "required": true
+    },
+    "FACEBOOK_CLIENT_ID": {
+      "required": true
+    },
+    "GOOGLE_APP_SECRET": {
+      "required": true
+    },
+    "GOOGLE_CLIENT_ID": {
+      "required": true
+    },
+    "JWTKEY": {
+      "required": true
+    },
+    "LINKEDIN_CLIENTID": {
+      "required": true
+    },
+    "LINKEDIN_CLIENTSERVICE": {
+      "required": true
+    },
+    "NODE_ENV": {
+      "required": true
+    },
+    "PRODUCTION_STAGE": {
+      "required": true
+    },
+    "SENDGRID_API_KEY": {
+      "required": true
+    },
+    "TWITTER_CONSUMER_KEY": {
+      "required": true
+    },
+    "TWITTER_CONSUMER_SECRET": {
+      "required": true
+    }
+  },
+  "formation": {
+    "web": {
+      "quantity": 1
+    }
+  },
+  "addons": ["heroku-postgresql"],
+  "buildpacks": [
+    {
+      "url": "heroku/nodejs"
+    }
+  ],
+  "stack": "heroku-18"
+}