Run script fails on HTTPS endpoints

When load testing a sock shop secured by HTTPS, there is no way to give the `https://` address as the script places the prefix `http://` on the host.

As a workaround, a user can execute `locust` directly, for example:

```
locust --host=https://sock-shop.example.com -f locustfile.py --clients 10 --hatch-rate=5 --run-time=1m --no-web --only-summary
```