Merge pull request #649 from sutra/develop

Obtain the id, method, params for signature from BTCRequest object directly rather than extract from request body by regular expression matcher, in BTCChinaDigest.
[hitbtc] Fix clientOrderId for DOGE, add tests
[hitbtc] Fix lot multipliers for currencies, change order quantity to BigInteger
Merge pull request #651 from rafalkrupinski/fix-hitbtc

Fix HitBTC
Make market order order type configurable
Merge pull request #652 from jheusser/bf_marginmarket

Bitfinex: make market order ordertype configurable (margin/exchange)
[BTCChina] Remove null from signature message.