Collect deferreds for processes manually
Collect deferreds for processes manually

JobType.start() no longer returns anything, which breaks _start(). This
commit fixes it again by not using deferreds return from start(), but
instead manually collection the deferreds from self.processes.

guidow/pyfarm-agent,pyfarm/pyfarm-agent,pyfarm/pyfarm-agent,guidow/pyfarm-agent,pyfarm/pyfarm-agent,guidow/pyfarm-agent