Fix imports

Removed datetime import, added os import and formatted flask imports.

Author: ismailmo1

app.py

@@ -1,5 +1,8 @@
-from datetime import datetime
-from flask import Flask, render_template, request, redirect, url_for, send_from_directory
+import os
+
+from flask import (Flask, redirect, render_template, request,
+                   send_from_directory, url_for)
+
 app = Flask(__name__)
 
 
@@ -26,4 +29,4 @@ def hello():
 
 
 if __name__ == '__main__':
-   app.run()
+   app.run()