Swap out fledgling Flask application for a Node Express one,

Investigation revealed that Web3.py couldn't read the events raise
by our smart contract. This was, apparently, a problem in the Solidity
compiler rather than Web3.py, but that's little consolation as it means
I can't use it.  Switching to a JavaScript backend because we know
Web3.js works ok, even though it means we'll have to shell out to
run the image fingerprinter.

.gitignore

@@ -1,3 +1,4 @@
 .idea
-.venv
+node_modules
+package-lock.json
 

web-server/app.js

@@ -0,0 +1,14 @@
+const express = require('express');
+const path = require('path');
+const logger = require('morgan');
+
+const app = express();
+
+app.use(logger('dev'));
+app.use(express.json());
+app.use(express.urlencoded({ extended: false }));
+
+app.get('/', (req, res) => res.redirect(301, '/index.html'));
+app.use(express.static(path.join(__dirname, 'static')));
+
+module.exports = app;

web-server/bin/www

@@ -0,0 +1,90 @@
+#!/usr/bin/env node
+
+/**
+ * Module dependencies.
+ */
+
+const app = require('../app');
+const debug = require('debug')('web-server:server');
+const http = require('http');
+
+/**
+ * Get port from environment and store in Express.
+ */
+
+const port = normalizePort(process.env.PORT || '3000');
+app.set('port', port);
+
+/**
+ * Create HTTP server.
+ */
+
+const server = http.createServer(app);
+
+/**
+ * Listen on provided port, on all network interfaces.
+ */
+
+server.listen(port);
+server.on('error', onError);
+server.on('listening', onListening);
+
+/**
+ * Normalize a port into a number, string, or false.
+ */
+
+function normalizePort(val) {
+  const port = parseInt(val, 10);
+
+  if (isNaN(port)) {
+    // named pipe
+    return val;
+  }
+
+  if (port >= 0) {
+    // port number
+    return port;
+  }
+
+  return false;
+}
+
+/**
+ * Event listener for HTTP server "error" event.
+ */
+
+function onError(error) {
+  if (error.syscall !== 'listen') {
+    throw error;
+  }
+
+  const bind = typeof port === 'string'
+    ? 'Pipe ' + port
+    : 'Port ' + port;
+
+  // handle specific listen errors with friendly messages
+  switch (error.code) {
+    case 'EACCES':
+      console.error(bind + ' requires elevated privileges');
+      process.exit(1);
+      break;
+    case 'EADDRINUSE':
+      console.error(bind + ' is already in use');
+      process.exit(1);
+      break;
+    default:
+      throw error;
+  }
+}
+
+/**
+ * Event listener for HTTP server "listening" event.
+ */
+
+function onListening() {
+  const addr = server.address();
+  const bind = typeof addr === 'string'
+    ? 'pipe ' + addr
+    : 'port ' + addr.port;
+  debug('Listening on ' + bind);
+}

web-server/package.json

@@ -0,0 +1,14 @@
+{
+  "name": "web-server",
+  "version": "0.0.0",
+  "private": true,
+  "scripts": {
+    "start": "node ./bin/www"
+  },
+  "dependencies": {
+    "cookie-parser": "~1.4.4",
+    "debug": "~2.6.9",
+    "express": "~4.16.1",
+    "morgan": "~1.9.1"
+  }
+}