Add --version option

Add --version option



https://code.launchpad.net/~clint-fewbar/juju/add-version-arg/+merge/127109

(do not edit description out of merge proposal)

[clint.byrum, 2012-09-29 16:33:47]

Please take a look.

[jimbaker, 2012-10-03 22:07:57]

LGTM with the minor. One thing I noticed is that I would expect the output on
stdout, not stderr, so that I can do this

export JUJU_VERSION=$(juju --version)

instead of 

export JUJU_VERSION=$(juju --version 2>1)

Of course this behavior of using stderr is just what argparse does. However, in
a completely random sampling of commands, most print to stdout (ls, xargs, bzr).
One notable exception: python, it uses stderr. Same with java -version.

However, supporting --version like this is going to have to work around the fact
that we use argparse to support subcommands. And anything dealing with
subcommands in argparse is possible, but way too complicated.

So, never mind, let's just do what argparse makes easy :)

https://codereview.appspot.com/6593044/diff/1/juju/control/__init__.py
File juju/control/__init__.py (right):

https://codereview.appspot.com/6593044/diff/1/juju/control/__init__.py#newcod...
juju/control/__init__.py:110: "--version", action="version", version='juju %s' %
(__version__))
version="juju %s" % __version__

would be preferable (we use double quotes uniformly in the Juju codebase).