Switch to using Google Drive SDK, closes #2047

I switched over to using the Google Drive SDK. Should hopefully fix some Google Drive issues along the way:

#3334, #2229, #2054

The authentication process changed from OAuth 1.0a to OAuth 2.0 so users need to reconfigure Google Drive storage. @karlitschek Need to include this info in the next release notes.

I believe this issue still exists: #2013 It will require a change in view.php

3rdparty: https://github.com/owncloud/3rdparty/pull/28

To test, checkout this branch and the 3rdparty branch and read this: https://developers.google.com/drive/quickstart-php You need a client id and secret for the authentication process in the external storage UI. It is also necessary to add authorized redirect URIs in the Google API Console for: 

* http://yourowncloud/index.php/settings/personal
* http://yourowncloud/index.php/settings/admin

I'll write this up in more detail for the docs later.

@apcloic @icewind1991 @MTRichards @a-schild