Merge "init: add class_restart"

  currently running, without disabling them. They can be restarted

  later using `class_start`.

`class_restart <serviceclass>`

> Restarts all services of the specified class.

`copy <src> <dst>`

> Copies a file. Similar to write, but useful for binary/large

  amounts of data.

  "sys.powerctl" system property, used to implement rebooting.

`restart <service>`

> Like stop, but doesn't disable the service.

> Stops and restarts a running service, does nothing if the service is currently

  restarting, otherwise, it just starts the service.

`restorecon <path> [ <path>\* ]`

> Restore the file named by _path_ to the security context specified

    return 0;

}

static int do_class_restart(const std::vector<std::string>& args) {

    ServiceManager::GetInstance().

        ForEachServiceInClass(args[1], [] (Service* s) { s->Restart(); });

    return 0;

}

static int do_domainname(const std::vector<std::string>& args) {

    return write_file("/proc/sys/kernel/domainname", args[1].c_str()) ? 0 : 1;

}

        {"chmod",                   {2,     2,    do_chmod}},

        {"chown",                   {2,     3,    do_chown}},

        {"class_reset",             {1,     1,    do_class_reset}},

        {"class_restart",           {1,     1,    do_class_restart}},

        {"class_start",             {1,     1,    do_class_start}},

        {"class_stop",              {1,     1,    do_class_stop}},

        {"copy",                    {2,     2,    do_copy}},