main: daemonize more thoroughly
main: daemonize more thoroughly

As described at http://software.clapper.org/daemonize/ ,
a daemon should chdir to / and close its FDs.

rfjakob/gocryptfs,davesteele/gocryptfs,rfjakob/gocryptfs,rfjakob/gocryptfs,davesteele/gocryptfs,davesteele/gocryptfs,rfjakob/gocryptfs