Fixed bug in adaptOrderType()

"buy" is not the server response.  It should be "bid".  Otherwise this method always returns OrderType.ASK
Changing trade.streaming.BTCChinaBalance.toString() method to be prettier.

Before, the method printed out a nasty string that prefixed the entire package name like:
com.xeiam.xchange...streaming.BTCChinaBalance@7f374, which is not a useful string.  The method is
now changed to behave like the toString() method in BTCChinaOrder of the same package.
Changing trade.streaming.BTCChinaBalance.toString() method to be prettier.

Before, the method printed out a nasty string that prefixed the entire package name like:
com.xeiam.xchange...streaming.BTCChinaBalance@7f374, which is not a useful string.  The method is
now changed to behave like the toString() method in BTCChinaOrder of the same package.
Merge branch 'toStringRequest' of https://github.com/bryan4887/XChange into toStringRequest

Conflicts:
	xchange-btcchina/src/main/java/com/xeiam/xchange/btcchina/dto/trade/streaming/BTCChinaBalance.java
Merge pull request #736 from bryan4887/bugfix

Fixed bug in BTCChinaAdapters.adaptOrderType()
Merge pull request #737 from bryan4887/toStringRequest

To string request