Refactored Example CLI with Symfony/Console

Hi,

I've refactored example_cli with console command support.  The PHP script claimed it needed symfony/console but it actually didn't implement that component at all.

Instead of just wrapping the existing functionality in a console command, I've used symfony/dependency-injection to split up the fetching/parsing of the data from the actual rendering in the command. 

Still needs: a bit more documentation & a formal review.

Install and use it (Shell commands):

```bash
composer update
chmod +x example/example_cli
example/example_cli phpoaipmh:example
```

Comes with a switch:
```bash
example/example_cli phpoaipmh:example --call=all
```
Valid options are: basic, exception, all, records, formats.