Disable HTTP keepalive or reduce idle timeout

[paulf69487623]

I was just doing a scan, and discovered that the HTTP client is doing HTTP keepalive by default. For our use case, we don't really benefit from this. We should disable it, or at least set the idle timeout to be very short. Eg, 10 seconds.

This will probably require us to use a specific http.Client with an http.Transport configuration.