Problem: security tests block on zmq_send

The expect_bounce_fail () helper assumed that messages could always
be sent. However in some cases zmq_send() blocks, due to there not
being any outgoing pipe. This changed in 77f5f7, where previously
there would be a pipe that kept trying to reconnect forever.

Solution: use a send timeout and check for EAGAIN if sending failed.
Minor trim of man page title
Merge pull request #1049 from hintjens/master

Minor fixes