Refactor OAuth2AuthenticationSerializer

[beckje01]

This is to allow easier override, the major change is byte[] serialize changing to Object serialize I wanted to change my Gorm classes and use Strings instead with JSON. This should be transparent to most users only someone extending OAuth2AuthenticationSerializer should be effected.

[bobby-vandiver]

The interface for OAuth2Authentication deserialize(byte[] authentication) should also be changed to reflect the type change since the serialized OAuth2Authentication instance will be passed to deserialize at some point. See OAuth2Authentication readAuthentication(String token) in GormTokenService for an example.

[beckje01]

Thanks, let me know if you would rather have this rebased and squashed.

[bobby-vandiver]

I would at least fix up your last two commits to avoid any confusion when checking out the history in the future. It looks like they're the same change anyway. Other than that, it looks good. 👍

[beckje01]

All squashed.