Fixes bitvc

Fixes a number of things:
* delete logback.xml @sutra 
* apply missing plaintest Uri to xchange-core needed when instantiating an exchange via reflection
* remove unnecessary parsing such that LTC/CNY works @zholmes1 
* most importantly @timmolter : make wallet balance consistent with "expected" long/short/flat semantics when using borrowing: Borrowing should not alter your main wallets balance, thus we subtract borrowed amounts from the main wallet. This is consistent with Bitfinex's wallet logic and is kind of intuitive:
  * When borrowing N bitcoin your position is flat which is reflected in a balance reduced by the borrowed amount. E.g. if you have 0 BTC in your wallet and you borrow, you still have 0 BTC in your main wallet.
  * When shorting N bitcoin your BTC balance will be negative/reduced by the shorted amount
  * When going long N bitcoin your BTC balance will be positive by the amount bought