Clean up old APIs and fix updated APIs

- Updated API calls to renamed BTSX->BTS
- Updated API calls to BTCTurk
- Removed MintPal exchange and with it the last Cloakcoin exchange data
source
- Removed Prelude exchange
- Removed Dogecoin/Euro pair no longer available from Kraken
- Removed Litecoin/Pound pair no longer available from Bittylicious