nfs_mount the Cloud Updates repo in nue_nfs

Fixes #59
Merge pull request #60 from mapleoin/updates-repo

nfs_mount the Cloud Updates repo in the nue_nfs cases
mkcloud: use explicit ssh options
mkcloud: we dont need to modify .ssh/config

with options now being passed explicitly to ssh
Merge pull request #63 from bmwiedemann/master

ssh hostkey rework
qa_crowbarsetup: Add local repos support

When $localreposdir_target is set, local repositories are used for crowbar
managed nodes and to setup the crowbar node itself.