implement `--version` and improve `setup.py`

Creates the `--version` flag, and implements an *import safe* way to retrieve it for packaging
It also parses the README so that it can be added as the `long_description` which is what will be shown in PyPi once the package is published.

Reference issue http://tracker.ceph.com/issues/8640

![screen shot 2014-08-04 at 3 29 58 pm](https://cloud.githubusercontent.com/assets/317847/3802326/f1882c68-1c0d-11e4-8838-e66af3d9aeee.png)