Merge branch 'develop' of github.com:timmolter/XChange into develop
Merge branch 'develop' of github.com:timmolter/XChange into develop
Add BTCTradeSession to ensure the polling service instancs, which using same API key, share the same secret data and nonce, and make all requests on one API key synchronized.
Add license header to the new files.
Merge pull request #484 from sutra/develop

Add BTCTradeSession to ensure the polling service instancs, which using same API key, share the same secret data and nonce, and make all requests on one API key synchronized.