[WIP] GB kraken stability

[askmike]

Kraken is not stable for a few different reasons. This PR aims to fix that!

fixes #2412.
fixes #2486.

• Fixes a bug between underlying kraken lib & gekko broker's retry mechanism. See always overwrite nonce nothingisdead/npm-kraken-api#63 for details.

[askmike]

Kraken API is so hard to work with...

2018-09-06 06:09:32 [HEDGE buy] done @~ 0.0007833
hedge summary: { price: 0.0007833,
  amount: 15.96,
  date: moment("2018-09-06T06:09:30.948"),
  side: 'buy',
  orders: 1,
  fees: { BNB: 0.00618675 },
  feePercent: 0.07500000000000001 }
API:Invalid nonce
Response code 502 (Bad Gateway)
API:Invalid nonce
API:Invalid nonce
API:Rate limit exceeded
API:Rate limit exceeded
API:Rate limit exceeded
API:Rate limit exceeded
API:Rate limit exceeded
API:Rate limit exceeded
API:Rate limit exceeded
API:Rate limit exceeded
API:Rate limit exceeded
API:Rate limit exceeded
API:Rate limit exceeded
API:Invalid nonce
API:Rate limit exceeded
API:Rate limit exceeded
API:Rate limit exceeded
API:Rate limit exceeded
API:Rate limit exceeded
API:Rate limit exceeded
API:Invalid nonce
API:Rate limit exceeded
API:Rate limit exceeded
API:Rate limit exceeded
API:Rate limit exceeded
API:Rate limit exceeded
API:Rate limit exceeded
API:Rate limit exceeded
API:Rate limit exceeded
API:Rate limit exceeded
API:Rate limit exceeded

[askmike]

Merging this!

I am still experiencing tiny issues, I'll push fixes directly upstream as soon as I reproduce and fix them!

[askmike]

@dugu-dugu @starkadd3r @danielm001 I have greatly improved kraken's stability now. Kraken's API is really hard to work with, things have improved since last year but not by much:

• Any API call can timeout (on cloudflare's side) and after that Gekko does not know whether what it tried to do succeeded or not. There is a ton of new logic that catches this and jumps through hoops to figure out if the previous call worked.
• The API is very slow and you hit rate limits very fast, on top of that because of very unstable network Gekko runs into "invalid nonce" errors quite often, which for some reason ARE counted towards rate limit usage.

Most kinks are out now, and I've done around ~200 successful trades now using this code.

[askmike]

Improving this is on hold, as Kraken suddenly disabled my account & API access...

https://twitter.com/mikevanrossum/status/1037963202728849408