ht_kvm.py contains the code for ganeti to work under kvm.
This patch also modifies Makefile.am to ship that file, and
lib/hypervisor/__init__.py to import it, and add kvm to the
hypervisors map.

Reviewed-by: imsnah

Add a new hypervisor type, HT_KVM, to constants, and register it in the
HYPER_TYPES set.

Reviewed-by: imsnah

This allows to configure a different path to the kvm binary. By default
/usr/bin/kvm is used, which is the one found in debian and ubuntu.

Reviewed-by: imsnah

StartInstance takes 'block_devices', not 'force' as its third argument.
Even if this is not used in the fake hypervisor it's better to have the
correct argument name to avoid confusion.

Reviewed-by: imsnah

Reviewed-by: imsnah

If a node hasn't been part of the cluster before being added it'll not
have the cluster's SSH key. This patch makes sure to accept those by
not aliasing the machine name to the cluster name.

Reviewed-by: ultrotter

Noded didn't release the job queue lock after initialising it. This
patch makes sure to unlock once the work is done.

Reviewed-by: ultrotter

This means commands will not take at least one second anymore.

Reviewed-by: ultrotter

This way clients can react faster to status or message changes and
don't have to poll anymore.

Reviewed-by: ultrotter

See the comment in the patch.

Reviewed-by: ultrotter

These will be used for job logs.

Reviewed-by: ultrotter

Reviewed-by: iustinp

Reviewed-by: iustinp

The lock should only be removed if ganeti-noded is going to quit.
Otherwise it needs to be kept to prevent another process from creating
it again while we're still holding the (removed) lock. This is due to
POSIX filesystem semantics.

Reviewed-by: iustinp

The code cleaning the queue will make use of it.

Reviewed-by: iustinp

Otherwise one might have archived jobs back in the list after a master
failover.

Reviewed-by: iustinp

This will be used to archive jobs.

Reviewed-by: iustinp

Another function will need to check whether its parameters
are job queue files.

Reviewed-by: iustinp

The lock will also be needed by another function.

Reviewed-by: iustinp

Reviewed-by: iustinp

Reviewed-by: iustinp

This way we can do locking when both noded and masterd are running
on the same machine, the latter holding an exclusive lock on the
queue.

Reviewed-by: iustinp

Reviewed-by: iustinp

Otherwise users might be confused by errors in log files.

Reviewed-by: iustinp

The job queue is now updated through its own RPC functions.

Reviewed-by: iustinp

Reviewed-by: iustinp

jobqueue_update: Uploads a job queue file's content to a node. The
most common operation is to upload something that we already have
in a string. Unlike in the upload_file function, the file is not
read again when distributing changes, but content has to be passed
as a string.

jobqueue_purge: Removes all queue related files from a node.

Reviewed-by: iustinp

JobQueuePurge() will be used by an RPC function.

Reviewed-by: iustinp

Reviewed-by: iustinp

feedback_fn wasn't passed to it.

Reviewed-by: iustinp

The job queue maintains its own node list and must be notified
when nodes are added/removed.

Reviewed-by: iustinp

By doing this we've a central place which coordinates what needs to be
done when adding or removing nodes. Another patch will add calls into
the job queue.

Two log messages move to config.py.

When removing a node, node_leave_cluster is now called after it has
been removed from the configuration and job manager. That way we're
sure not to access the node again after files have been removed.

Reviewed-by: iustinp

These functions will be used to notify the queue about newly added
or removed nodes.

Reviewed-by: iustinp

The job queue now maintains its own list and is updated when
nodes are added or removed from the cluster.

Reviewed-by: iustinp

The code makes sure not to include the master in the list.

Reviewed-by: iustinp

The job queue must be called from cmdlib when adding or removing
nodes to the cluster. Moving it to the context objects makes
this possible.

Reviewed-by: iustinp

Old job files shouldn't be left on nodes removed from a cluster.

Reviewed-by: iustinp

Reviewed-by: iustinp

Reviewed-by: iustinp

Reviewed-by: iustinp