added JobChain for client-side job dependency graphs (to be used by tests)
added JobChain for client-side job dependency graphs (to be used by tests)

beni55/disco,mozilla/disco,discoproject/disco,simudream/disco,scrapinghub/disco,pooya/disco,mwilliams3/disco,discoproject/disco,ktkt2009/disco,beni55/disco,pavlobaron/disco_playground,discoproject/disco,oldmantaiter/disco,beni55/disco,ktkt2009/disco,ktkt2009/disco,discoproject/disco,seabirdzh/disco,mozilla/disco,beni55/disco,pooya/disco,scrapinghub/disco,ErikDubbelboer/disco,pavlobaron/disco_playground,ErikDubbelboer/disco,pombredanne/disco,pombredanne/disco,mwilliams3/disco,beni55/disco,oldmantaiter/disco,pooya/disco,ErikDubbelboer/disco,seabirdzh/disco,ErikDubbelboer/disco,ktkt2009/disco,pooya/disco,mwilliams3/disco,pombredanne/disco,simudream/disco,pombredanne/disco,seabirdzh/disco,seabirdzh/disco,scrapinghub/disco,mozilla/disco,mwilliams3/disco,oldmantaiter/disco,mozilla/disco,oldmantaiter/disco,simudream/disco,scrapinghub/disco,pavlobaron/disco_playground,pombredanne/disco,pavlobaron/disco_playground,seabirdzh/disco,simudream/disco,ktkt2009/disco,oldmantaiter/disco,simudream/disco,discoproject/disco,mwilliams3/disco,ErikDubbelboer/disco