Support Retries for Network Connection Errors on Browser

[ajtran]

It seems like this is already supported for server side. It would be nice to have this supported on the browser as well.

[tomaszn]

This feature would be very useful for "Hybrid Mobile Applications" which work also offline.
It was already suggested in #316 a year ago.

[rokob]

We actually already retry in certain situations because the underlying queue mechanism is shared across server/browser. However, we don't attempt to write to durable storage in the face of a persistent issue nor do we do any kind of backoff. The fix here would most likely to be adding exponential backoff and upping the number of retries. A later fix might be to write to something offline like local storage and sending it later, but I doubt the actual usefulness of those errors. It would be help for the PWA situation, but I think there are quite a few other things we would need to address as well.