[ALL] Add Gearman KEEPALIVE options

This requires the lastest development version of python-gearman
to support the new keepalive options. Using these options (off
by default) will solve the problem when the Gearman job server
gets paused/unpaused in a cloud environment, but the clients and
workers never recognize that they are indeed disconnected.

WARNING: Not backwards compatible with older versions of the
python-gearman driver, even if the SSL and keepalive options
are not specified. This is a change in behavior.

Change-Id: Ic8db6676f7408364b6fe9a8690deb72bb6e2772c