updated dependencies versions
updated more dependencies versions
revert dropwizard version 0.6.2 -> 0.6.1 as 0.6.2 caused breaking errors
added JSON functions to README.md
added Ask definitions & altered CurrencyPair representation
added rest of Ask implementation
minor change to description
cleaning / refactoring: BuyOrder and SellOrder ... : maintaining consistency so to not have bid/buy sell/ask/offer mixed class names like BidOrderDescriptor conflated with BuyOrder.   Bids and Asks should only exist in context of the order book.
more BidOrder -> BuyOrder refactoring.  Tests now pass.
Minor update to documentation bid/ask vs buy/sell