Moved sources from com.xeiam.xchange to com.xeiam.xchange.btccentral
Fixed imports in xchange-btccentral.
Moved Bitbay fources from com.xeiam.xchange to com.xeiam.xchange.bitbay
Moved sources for BitMarket from com.xeiam.xchange to com.xeiam.xchange.bitmarket
Moved sources for hitbtc from com.xeiam.xchange to com.xeiam.xchange.hitbtc
Merge pull request #424 from kpysniak/packages

Moved packages for Bitbay, Bitmarket, BTC Central and HitBtc