[1.x] Uncache folders, get drive service, empty trash

[erikn69]

• getService() added
  Closes Access to Google_Service_Drive property #27, useful in laravel's facade because $service creation is in a ServiceProvider,
  example Storage::disk('google')->getDriver()->getAdapter()->getService()

• emptyTrash(array $params = []) added
  Closes Delete forever ? #28, bridge to Google_Service_Drive's emptyTrash(for laravel),
  example Storage::disk('google')->getDriver()->getAdapter()->emptyTrash()

  the issue is the storage become full before a month

• uncacheFolder($path) added
  Closes Error while creating folder after deleting it from gdrive #29, useful on concurrent laravel's jobs, also it can be used like a workaround for avoid duplicity forcing to take first folder always(performance cost, but on queued jobs maybe doesn't matter, can be added something like this for avoid duplicity always?)

  Unfortunately Google Drive allows users to create files and folders with same (displayed) names

  Example for #29 :

$disk=\Storage::disk('google');    
$disk->createDir('test/testa'); //create dir, gets id to cache if it's already exists
//manually delete o permanently destroy on drive without adapter, 
//also maybe another concurrent thread could create a directory with the same name first, now this is a duplicate
$dir=$disk->getDriver()->getAdapter()->getMetadata('test/testa');
$disk->getDriver()->getAdapter()->getService()->files->delete($dir['id']); 
//uncache
$disk->getDriver()->getAdapter()->uncacheFolder('test/testa'); 
//refresh folder id and put file(duplicates stays empty because get first on refresh, if directory was deleted, it creates a new one)
$disk->put('test/testa/file.txt', 'Contents1'); 

still might lead to unexpected problems on concurrent delete, but can it helps to handle duplicates on createDir?