[2] native "kraken" integration should not restrict markets

[nikhilsaraf]

see last set of comments here: #421

kraken currently limits markets, whereas it is not limited on centralized exchanges. this is because of the API limitations of kraken that requires us to manually override asset names in a custom asset converter function.

for this task we should find a list of all the names for each asset and update KrakenAssetConverter and KrakenAssetConverterOpenOrders to expand the options available.

[Arno500]

It seems that list is available @ https://api.kraken.com/0/public/AssetPairs
It's also available in the API client library as a public API.
The wsname key contains the name of both of the assets, separated by a /.

[nikhilsaraf]

@Arno500 are there any assets you want to trade using Kelp but which are not currently supported?

[Arno500]

@nikhilsaraf Yes, I'm in Europe, so using EUR :)