Process &block parameter in Logger.add rather then Event.initialize,

 before silencing. Thus, allowing all messages to be processed by silencer, and also, logging messages from calls that only use a block parameter.

Eg. Cequel gem; I tried using Yell with Cequel, but no messages were logged by the Cequel gem - turns out they call debug/warn only with a block param, no actual messages array, as seen in [RequestLogger.rb#L42](https://github.com/cequel/cequel/blob/master/lib/cequel/metal/request_logger.rb#L42).