Moves the initialisation of time module inside the initialisatiion of
vmstates. This change the initialisation order of the modules (time mod
now comes last).

heartbeat_intr has been moved from os.c to vm.c since it is onlyy used
during the initialisation of time mod.

 On branch para
 Changes to be committed:
    modified:   lib/os.c
    modified:   lib/setup.c
    modified:   lib/vm.c