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