Added 'loglevel' command

This allows clients to alter the daemonproxy logging threshhold
on the fly.
Improved some test cases that were failing incorrectly
New signal delivery mechanism - fixes #15

Signals are now stored in a struct that includes timestamp and count.
Each controller keeps track of the timestamp of the last signal it
saw, and delivers them to the controller in a reliably way, so that
a full pipe can't cause the loss of a signal.