Add Arch and CentOS buildslaves to the swarm, move Ubuntu 13.10 -> 12.04
Add Arch and CentOS buildslaves to the swarm, move Ubuntu 13.10 -> 12.04

staticfloat/julia-buildbot,kshyatt/julia-buildbot,kshyatt/julia-buildbot,yuyichao/julia-buildbot,yuyichao/julia-buildbot,staticfloat/julia-buildbot