Add retry_time parameter instead of hardcoded 5 retries

[djaksic-reef]

Add retry_time parameter to retry for some period (in minutes) when an upload or download fails, instead of hardcoded 5 retries

https://reeftechnologies.atlassian.net/browse/B2-3

[agoncharov-reef]

LGTM.

On b2-sdk side I would rather use timedelta type instead of int minutes, but it's out of scope of this review. Just a quick note.

Also, you're adding some parameter to CLI which should appear in low-level Download/Upload manager. I already wrote a test for it long time ago, I think you should add your retry-for parameter check there too. Please have a look at test_passing_api_parameters :)

[ppolewicz]

I really think the resolution should be seconds, not minutes

[djaksic-reef]

I am changing to seconds. What could be the default retry time, 300 seconds?

[djaksic-reef]

I changed to seconds and added test to test_passing_api_parameters. It was really helpful. My original code wasn't passing retry_time to B2API :(