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

![screen shot 2013-07-30 at 11 18 42 am](https://f.cloud.github.com/assets/148708/877364/b5ac0f02-f8f0-11e2-8c9b-7c36f4ac04d3.png)