update instructions for running system tests on OS X
update instructions for running system tests on OS X

ContainerSolutions/minimesos,mwl/mini-mesos,ContainerSolutions/mini-mesos,ContainerSolutions/minimesos,mwl/mini-mesos,ContainerSolutions/mini-mesos,jitpack-io/mini-mesos,ContainerSolutions/minimesos,jitpack-io/mini-mesos