Retry on failed request to bank

[yoyostile]

We could use something like https://github.com/nfedyashev/retryable.
Would be great to fix this.

[bumi]

How should this be done? Do we want to do that automatically or should this be a configuration option and somehow be transparent to the user.

I am a bit worried about some unintended side-effects (whatever could happen if we send the request twice). Does the API consumer somehow need to be informed about a potential failed request and its response?
Generally I'd see this more of a client responsibility. A ebics box client wrapper could for example retry sending the request to the box in case of an error.

thoughts?