deploy: Use one shared dir instead of three

Until now we had pithos_dir, archi_dir and image_dir explicitly
exported by the NFS component. This is practically useless.

Let NFS server export only shared_dir (e.g. /srv) so that everything
under it is shared across NFS clients.

Signed-off-by: Dimitris Aragiorgis <dimara@grnet.gr>
deploy: image_dir -> vcluster_dir in deploy.conf

..so that it does not get overridden by image_dir in synnefo.conf.

This dir is used to keep locally the disks of the virtual cluster VMs.

Signed-off-by: Dimitris Aragiorgis <dimara@grnet.gr>
ci: Update schema configuration files

..to comply with the latest deploy changes.

Signed-off-by: Dimitris Aragiorgis <dimara@grnet.gr>
deploy/ci: Let extra_disk be /dev/vdb by default

In case of --autoconf the deployment is done on node1. This
node should not have an extra disk (currently ci cannot create
instances with 2 disks).

This way the only difference between snf-deploy and snf-ci conf
files is the testing_vm option.

Signed-off-by: Dimitris Aragiorgis <dimara@grnet.gr>
deploy: Fixes related to the GanetiDev component

Install the deb and cabal packages required for the latest ganeti
version (master branch of official repo).

Clone both official ganeti and snf-ganeti under config.shared_dir
(i.e. /srv/src). In ganeti-qa dev node is the same with nfs
so all qa nodes will see the same src and will be able to install
it from source (make install).

Signed-off-by: Dimitris Aragiorgis <dimara@grnet.gr>
deploy: Exit if required components fail to setup

Do not try: except: during installation of the required components
otherwise deploy could silently fail and continue execution.

Signed-off-by: Dimitris Aragiorgis <dimara@grnet.gr>
deploy: Introduce helper context methods

..for getting all nodes, all ips and cluster nodes of each context.

Use find_all_nodes() config method that recursively parses
corresponding section options of the requested setup.

Signed-off-by: Dimitris Aragiorgis <dimara@grnet.gr>