Add proper shebangs and block comments

imgupload.py

@@ -1,3 +1,9 @@
+#!/usr/bin/env python3
+"""
+imgupload.py
+
+Flask application for processing images uploaded through POST requests.
+"""
 from flask import Flask, request, jsonify, abort, Response
 from cryptography.fernet import Fernet
 from flask_api import status