Make Trades comparator static
[Bitfinex] Exception handling

All error messages returned by Bitfinex are now caught and thrown as an
ExchangeException with the message from Bitfinex.
[Poloniex] Account service exception handling

I will handle trade service exceptions once ResCU is able to parse
non-400 responses as an exception.
Merge pull request #641 from zholmes1/develop

Exception Handling
Merge pull request #640 from jheusser/static_comparators

Make Trades comparators static
[Bitfinex] Mute cancel order exception
Merge pull request #642 from zholmes1/develop

[Bitfinex] Mute cancel order exception