[PoC][Console] Add progress indicator helper

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | yes
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | *todo*
| Fixed tickets | n/a
| License       | MIT
| Doc PR        | *todo*

A lot of work needs to be done still but thought I would get some comments on this idea.

Example code:

```php
$progress = new ProgressIndicator($output);
$progress->start('Starting...');

for ($i = 0; $i < 100; $i++) {
    usleep(25000);
    $progress->progress();

    switch ($i) {
        case 20:
            $progress->setMessage('Just started...');
            break;
        case 50:
            $progress->setMessage('Half way...');
            break;
        case 90:
            $progress->setMessage('Almost Done...');
            break;
    }
}

$progress->finish('Done.');
```

Screenshot:

![output](https://cloud.githubusercontent.com/assets/127811/4511167/95302026-4b31-11e4-824e-5cb26f96e4cb.gif)