Develop kraken

I removed the default demo account because it was giving me an invalid nonce. possibly just a timezone difference thing if someone else is using it.  Tested with my account and it works just fine.  

In KrakenMarketDataService I noticed an IOException was getting caught and wrapped into an ExchangeException, I changed this to just throw the IOException.  I feel that ExchangeExceptions should only be used to reflect known errors by the exchange, i.e., an incorrectly formatted price.

For the most the new raw version isn't very user friendly with return values of like Map<String, String[][]>.  Given that, and also your comment on https://github.com/timmolter/XChange/issues/280.  I am going to work on some better deserialization and also expanding the Kraken specific features and types, i.e., stop-loss, take-profit, stop-loss-limit.

Kraken offers ticker data for either that last day or that last 24 hours.  Currently the adapter picks the last day for everything except volume which it uses the last 24 hours??  I think it makes since to use the last 24 hours for everything, but I'm not sure how to be objective about it, except that there is no concept of trading day with digital currency.

whew, ok, other than that everything should be good to go for the purpose of the raw/generic re-design.