Added error handling to BTCChina
Added Null checking for BTCChinaResponse
Resolve conflicts
Merge pull request #5 from timmolter/develop

Merge changes
Added BTCChinaError DTO, moved checks to BasePollingService
Merge branch 'develop' of https://github.com/timmolter/XChange into timmolter-develop

Conflicts:
	xchange-btcchina/src/main/java/com/xeiam/xchange/btcchina/service/polling/BTCChinaAccountServiceRaw.java
Merge branch 'timmolter-develop' into develop
Merge pull request #469 from ObsessiveOrange/develop

Added error handling to BTCChina