Improve messages when running refinerycms command with various options.

This also:

* shows help message when no arguments are specified
* adds -h (for --help) shortcut to see help message
* adds -v, --version to see current gem version
* shows unknown option message for not known options

![screen shot 2013-07-30 at 11 14 10 am](https://f.cloud.github.com/assets/148708/877349/1e5bb7b0-f8f0-11e2-9b06-ad8e217bd20c.png)