[medium/bug] ignore offline agents in ActiveAgentsByQueue
[medium/bug] ignore offline agents in ActiveAgentsByQueue

avoids returning offline agent information to killDupAgents, in
circumstances where the returned data includes only one online agent
with several offline agents, we could end up sending a kill notice to
the only online agent.

rezen/mig,ameihm0912/mig,mozilla/mig,yvesago/mig,mozilla/mig,mozilla/mig,mozilla/mig,sunnygkp10/mig,ameihm0912/mig,sunnygkp10/mig,jboyer2012/mig,yvesago/mig,jboyer2012/mig,mozilla/mig,sunnygkp10/mig,ameihm0912/mig,rezen/mig,sunnygkp10/mig,rezen/mig,yvesago/mig,rezen/mig,jboyer2012/mig,yvesago/mig,jboyer2012/mig