removed Bitstampede::Entities::Base.keys

Seems unnecessary, without it the code looks clearer
fixed small bug
comment about nounce should no be reused
added gem "awesome_print" and some comments
transactions :)
Merge branch 'transactions' into lets_see
added some error samples, and the bitstamp api (usefull when site was offline)
[untested] tried to cleanup json parse and errors

Could not test because bitstamp site is overloaded... there is a bitcoin
bubble-burst throughout the day...
unified error handling, split PrivateApi PublicApi, added ticker, started general_order_book (incomplete)
BitstampPriateApi#balance --> user_balance
renamed bitstampede.rb --> Bitstampede.rb
renamed mapper.rb --> Mapper.rb
renamed net.rb --> Net.rb
renamed standarderror.rb --> StandardError.rb
renamed nonce_generator.rb --> NonceGenerator.rb
renamed base.rb --> Base.rb
renamed order.rb
renamed ticker.rb
renamed transaction.rb
changed BitstampPrivateApi#transactions into user_transactions