Prepare for Heroku deployment

- Heroku will bind the app to $PORT

- Add parameter to API to be able to customize the background color of the svg

- Add parameter to API to be able to customize the border color of the svg

- Add SetUp.md section on how to customize your card with URL parameters

Update SetUp.md with a section on how to customize the card

app.json

@@ -0,0 +1,30 @@
+{
+    "name": "novatorem",
+    "description": "Realtime profile Readme displaying currently playing song on Spotify using the Spotify API.",
+    "scripts": {
+        "postdeploy": "gunicorn --workers=1 api.spotify:app"
+    },
+    "env": {
+        "SPOTIFY_CLIENT_ID": {
+            "required": true
+        },
+        "SPOTIFY_REFRESH_TOKEN": {
+            "required": true
+        },
+        "SPOTIFY_SECRET_ID": {
+            "required": true
+        }
+    },
+    "formation": {
+        "web": {
+            "quantity": 1
+        }
+    },
+    "addons": [],
+    "buildpacks": [
+        {
+            "url": "heroku/python"
+        }
+    ],
+    "stack": "heroku-20"
+}