Add some crowbar client nodes to /etc/hosts

For easier ssh matters
Add "intr" option for NFS mounts

Allows to abort hanging NFS calls (that otherwise wouldn't be
interruptible due to the "hard" default option).
Set NFS mount r/w operation default blocksize to 8k

Should obtain better performance.
Allow having "rw" NFS mounts.
Merge pull request #25 from saschpe/master-convenience

More stuff for NFS mounts and /etc/hosts