This patch does two things:
- Add gnt-cluster modify
- Add --no-lvm-storage option to gnt-cluster init

Reviewed-by: iustinp

Author: manuel.franceschini
Reviewed-by: iustinp

This patch improves the ‘gnt-cluster verify-disks’ command by adding
support for detecting broken volume groups and missing logical volume
names.

As such, we don't try anymore to activate disks for instances that are
not likely to succeed anyway, and instead report them.

Reviewed-by: schreiberal

This patch implements a first proof-of-concept for HVM support in Ganeti.
Due to the nature of this patch, it is intended for test environments
only.

Reviewed-by: iustinp

This patch adds the OpVerifyDisks handling in mcpu.py and the
verify-disks command in the gnt-cluster script, which for every instance
computed by LUVerifyDisks submits a new OpActivateInstanceDisks request.

Reviewed-by: imsnah

- When line wrapping is needed, move spaces to the next line.
- Remove embedded line breaks from error messages.

Reviewed-by: schreiberal

This patch adds a search command for locating tags on all objects of the
cluster using a regex pattern.

Reviewed-by: aat

This patch adds a '--from' option to the {add,remove}-tags commands that
allows the command to read from a file or from stdin (when passing a
dash for the filename).

Reviewed-by: imsnah

This patch adds generic functions for tag manipulations to cli.py and
modifies gnt-{cluster,node,instance} to export {list,add,remove}-tags
commands that use those.

Reviewed-by: imsnah

This patch improves the AskUser function by allowing it to:
 - choose from multiple choices (instead of only y/n)
 - give help to the user
 - preserve line breaks and whitespace formatting in the message

With this patch, an instance removal looks like this:
root@xen-test1-4:~# gnt-instance remove tsetest1
This will remove the volumes of the instance tsetest1 (including
mirrors), thus removing all the data of the instance. Continue?
y/[n]/?: ?
 y - Perform the operation
 n - Do not perform the operation

This will remove the volumes of the instance tsetest1 (including
mirrors), thus removing all the data of the instance. Continue?
y/[n]/?: y

The patch also removed the _ask_user member of the opts argument, since
external code was using it (and thus it makes no sense for it to be a
private member); now gnt-* scripts are using the AskUser function
directly.

Reviewed-by: ultrotter

This patch adds a new OpCode (and corresponding LU) that implements the
cluster rename functionality.

This is done by shutting down the master role, making the needed sstore
modifications and distributing the changed files to all nodes, and then
re-enabling the master role.

The modification to the man page of gnt-cluster also moves the section
on gnt-cluster destroy in order to correct alphabetical ordering.

Reviewed-by: imsnah

This function used a hand-coded ssh call to remote nodes. Fix it to use the
ssh.SSHCall function, and in the process drop the command field from the
results, as it's too verbose and we can use (in gnt-cluster) what we passed in.

Reviewed-by: schreiberal

This changes the raising of exceptions from:
  raise Exception, value
to
  raise Exception(value)

as the first form will be removed in python-3000 and the second form is
preferred now.

The changes also involve a few cases of changing from raising standard
exceptions and use our own ones.

The new version also fixes many pylint-generated warnings, especially in
ganeti-noded where I changed many methods to @staticmethod.

There is no functionality changed (barring any bugs).

Reviewed-by: iustinp

Reviewed-by: iustinp

runnable on non-master nodes (and remove the list of instances and nodes
returned by it, that information can be retrieved by other opcodes).

Also, remove the node/instance list from "gnt-cluster info" as it
doesn't make sense to duplicate this information.

Reviewed-by: imsnah

Reviewed-by: iustinp

  - move the master node name from the ConfigWriter to SimpleStore (all
    nodes need this, and it was the only thing pulled in from the
    ConfigWriter on nodes)
  - fix mcpu.py and the testing w.r.t. this change; for testing, rename
    the fake_config.py to mocks.py and add a FakeSStore object
  - then add a ganeti-master script which can be run on any node at boot
    and which will not do anything if not master on start (on stop it
    will still try to remove the ip address)
  - also add a new cluster-wide variable (master_netdev) that determines
    on which interface we add this ip address; it's customizable at
    cluster init time
  - also remove the cluster name file which was separately handled from
    ssconf (not needed anymore)
  - remove the master init.d links from the list of config files as this
    is not our responsibility now

Reviewed-by: imsnah