rmid should annotate child process output

Currently, rmid redirects child process output streams (out and err) to
System.out and System.err respectively. Since, rmid simply redirects the
output, it is difficult to figure out which output came from which child
process. Instead, rmid should add an annotation (to the beginning of each
line of output sent from the child process) that labels the line to distinguish
it from output originating from other child processes.