Add function: getRecentHistory()

Add getRecentHistory() function to the library to return the recent messages in the room.

### Example
```php
use GorkaLaucirica\HipchatAPIv2Client\Auth\OAuth2;
use GorkaLaucirica\HipchatAPIv2Client\Client;
use GorkaLaucirica\HipchatAPIv2Client\API\RoomAPI;

$auth = new OAuth2('APITOKENHERE');
$client = new Client($auth);

$roomAPI = new RoomAPI($client);
$messages = $roomAPI->getRecentHistory(123456, array('max-results' => 1));
```

*Tests updated to include, additional functionality.*

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