create endpoint for changing username

#68

backend/index.js

@@ -277,4 +277,19 @@ app.get('/API/resourcelist', function (req, res) {
     return res.send(resourceList);
 });
 
+app.post("/API/user/setname", function (req, res) {
+    let { email } = req.body;
+    if (email) {
+        if (DEBUG) return res.status(status.OK).send();
+        connection.query(`UPDATE user SET email = ${mysql.escape(email)} WHERE email = ${mysql.escape(req.user.email)}`, function (err, rows) {
+            if (err)
+                return res.status(status.INTERNAL_SERVER_ERROR).send("the username seems invalid or already taken - if you think this is an error contact the sys admin");
+            req.user.email = email;
+            return res.status(status.OK).send("username changed");
+        });
+    } else {
+        return res.status(status.BAD_REQUEST).send("invalid data supplied");
+    }
+});
+
 app.listen(3001);