If an uncaught exception is thrown currently it destroys the calling
thread. This patch changes the behaviour to failing the current job,
logging a message, but trying to keep the daemon up.

Reviewed-by: imsnah

When a Job raises a ganeti exception a message is printed but nothing is
reported in the job itself. It's better to update the job status, thus
notifying the client, possibly polling for the job result, of what went
wrong.

Reviewed-by: iustinp

- Add a docstring to IOServer's constructor
- Add argument description to PoolWorker's and JobRunner's ones

Reviewed-by: iustinp

This patch adds a mechanism to disable utils.RunCmd in selected
programs. This is needed in the master daemon unless we confirm
threading doesn't pose any problems.

This makes cluster init fail, but creating new trunk clusters is anyway
broken at the moment.

Reviewed-by: ultrotter

This patch removes the lock and the lock options from cli.py and moves
them to the master.

Later during development we can remove it completely, but for now it's
good to protect any other tool that uses the lock directly.

Reviewed-by: imsnah,ultrotter

This patch converts the cli.py SubmitOpCode method to use the unix
protocol and thus execute the opcodes via the master.

The patch allows a partial burnin to work with the master. Currently the
query opcodes, since they are executed via the SubmitOpCode, are
executed inside a job too, which is suboptimal, but they work fine.

The cmd lock has been removed from the master, but the cli.py still
takes the lock. This is ok for this in-progress patch (since the master
still has only one executor thread). This will be fixed in a future
patch.

Reviewed-by: ultrotter

This patch changes the definition of a job and introduces per-opcode
results.

First, the result and status fields of a job are condensed into a single
'status' attribute. Then, we introduce an opcode status and one result
list, that allow jobs to return values.

The gnt-job script is also modified to allow these new fields to be
queried.

Note that the patch changes the opcode field to op_list, and it changes
its return value from string to a list of (serialized) opcodes.

Reviewed-by: ultrotter

This patch adds checks for the master role and daemonize support to
ganeti-masterd.

The patch modifies the startup/shutdown of the server because:
  - we want bind()/listen() to the master socket to occur before forking
    so that we can return a correct exit code and write messages to
    stderr
  - but we want thread startup to occur after fork(), otherwise python
    threading gets confused

The patch also has some small cleanups:
  - remove the unix socket after closing it, so we don't need to remove
    it manually
  - instead of just telling the threads to terminate via the new_queue,
    we also join() them so that the logs show what thread clinging to
    life
  - the daemon logs to its own logfile now
  - there is command line parameter support :)

Reviewed-by: imsnah

This patch adds a very basic gnt-job script that allows job querying.
This goes on top of the previous master daemon patches.

Currently, because of the not-changed cmd lock, you can't query the jobs
as long as a job is running - you have to rm the cmd lock and then you
can query the jobs.

Reviewed-by: imsnah

This patch adds a very in-progress master daemon. This needs to be
launched manually, does not background itself, but can be used for
opcode execution.

Also parts of this code should be moved to luxi.py.

Reviewed-by: ultrotter