Throttle Initialization-fetching

[Qqwy]

To make sure we don't open up our application for a DDoS, we should fetch data slowly, also during the initial initialization-fetch: Fetch in small batches of data, and then take a minute before fetching the next batch.

[InputUsername]

In addition, we should not start fetching new data until historical data is retrieved, otherwise EndpointCalls will end up in the wrong order.

[Qqwy]

@InputUsername That second notice is implemented in PR #176

[Qqwy]

This is nice-to-have, but currently the one thing that blocks adding Zeeguu to the project.