Two methods added to AMQPConnection:
+ attachSignal - setup signal handler
+ detachSignal - setup default handler

What is this slight modification about?
Worker/Cosumer listens for messages. I'd like to have a possibility to
check current status of the script.
Thanks to that modification, I can declare my own callback which
performs desirable action in response to signal ex. SIGUSR1.
I can't do it with pcntl extension (consume is blocking method).

This neat feature makes administrative work a bit easier.