Log on disk wasn't copy on install, so the shutdown destroy everything.
#18 #17

It's maybe the pb of #17

- Since the cron job could be called before the user reboots after
  install (or if log2ram is disabled), we check that the hdd log
  location exists before syncing.

- Copy the log2ram.hourly sync script to cron's hourly directory on
  install.

no x flag for logr2ram.server