Enhance golo golo command to support folders and specific module

`--files` parse folders to load golo files
`--module` is added to specify a Module name for the main function

this command is valid
```sh
$ golo golo --files samples/ --module hello.World
Hello World!
$
```
And
- shell completion updated with --module
- documentation for this enhancement
- some samples have a new module name (to avoid duplication in classpath)