Introduce retry policy to http requests

[killy971]

In the current implementation, each http request is only tried once, with the connection and read timeouts each set to 1 minute.
When the http request fails, it is never retried and no result is returned.

This change will improve the resiliency by introducing a retry policy to each http call.
The https://github.com/Soostone/retry library will be used for the implementation.

Feature branch: retry-http-requests

[killy971]

This change actually only covered the GET request (wait_url), and not the initial POST request.