Never forget _netdev with glusterfs mounts

When adding GlusterFS share to /etc/fstab do not forget to add "_netdev" to the mount options. Otherwise on next boot your system will just hang! Actually there doesn't seem to be a timeout. That would be nice too. As a side-note: do not forget that Ubuntu 12.04 doesn't care about the "_netdev" even. So network is not guaranteed to be up when mounting. So an additional upstart task or init script is needed anyway. But you need "_netdev" to prevent hanging on boot. I also have the impression that this only happens with stock kernel 3.8.x and not with 3.4.x!