The executor doesn't need to set the timeout

It's up to the driver to set a suitable timeout for polling the broker,
this one can be different that the one requested by the driver
caller as long as the caller timeout is respected.

This change also adds a new driver listener API, to be able
to stop it cleanly, specially in case of timeout=None.

Closes bug: #1400268
Closes bug: #1399257
Change-Id: I674c0def1efb420c293897d49683593a0b10e291
Merge "The executor doesn't need to set the timeout"