Implemented all Bitfinex order types

In BitfinexTradeServiceRaw, changed the boolean onMargin parameter to a
BitfinexOrderType parameter. Users can now use
BitfinexTradeServiceRaw.placeLimitOrder, passing a LimitOrder and a
BitfinexOrderType, to place any type of order that Bitfinex supports.
Alphabetize imports
Update BitfinexTradeService.java
Merge pull request #463 from zholmes1/develop

Implemented all Bitfinex order types