Tweak http response handling in cronrequest()

[tom--pollard]

As ServeHTTP doesn't write a response until all packages from a current 'poll' session have been processed, the current timeout of 10s on the cron GET request times-out waiting for the respons headers.

level=info msg="http request failed: Get \"http://localhost:8080\": context deadline exceeded (Client.Timeout exceeded while awaiting headers)

The error is non-fatally handled, as such this isn't a critical issue however it obviously should be handled more gracefully, especially when writing to the log.

[tom--pollard]

The default behaviour of having no timeout could be suited to this usecase (as the response holds no substantial value to it), however this is risky when running the requests in goroutines (via the cron package) as they could be left continually waiting to exit if the localhost httpserver is down for whatever reason.