Added the option of including a expiration pushed via a stream and
tests.
Avoid leaking error handlers by tracking open sockets

Instead of adding an error handler for each socket, keep track of the
sockets when created, and propagate errors.
Merge branch 'add_message_expiration_to_push_sockets' of https://github.com/wolfeidau/rabbit.js into issue41
Refunge the expiration test, and extend expiration opt to pub sockets

Moves _acceptOpt to the prototype (of each socket), where it ought to
be.