Fixing hanging uploads

[tanema]

fixes #790 fixes #801 fixes #810

Re-evaluating the retry mechanism, I realized that there was a fault in the if statements where the attempt count would only get incremented on timeouts and not for all other errors like 500s.

Here is the logic now

• if non-retryable http status (success or otherwise), return (100 =< code <= 428)
• if 499 then use retry-after header to block all requests until after the time limit then continue without incrementing attempt because this is not an error. I don't want to fail out of uploads because of 499s
• If request failed with host error, its fatal, return
• Otherwise, increment attempt and try again

Warn Checklist

• [ ] This changes the interface and requires a Major/Minor version change.
• [x] I have :tophat:'d these changes by using the commands I changed by hand.
• [ ] I have added a dependancy to the project.
• [ ] I have considered any potential impact on node-themekit

[andyw8]

@tanema were you able 🎩 locally? Guess it may be awkward.

[tanema]

I tophatted it with slow/timeouts and rate limits as well as the no host error/no connection errors.