refactor client functionality into Client class

Client is a Celluloid supervisor monitoring a connection pool
add Ridley::open delegator
pass connection object and not supervisor tree to resources
remove thread_count option from client
add #sync alias to client for evaluate
update acceptance specs to use Ridley.new instead of Ridley.connection
move client_key validation to Client initializer to avoid actor crash
fix broken node resource spec
Merge pull request #47 from reset/client-class

refactor client functionality into Client class