Implement hasBeenCancelled() in Google2Client

Tested in production environment, a little different to FacebookClient as the 
```
context.getRequestParameter(OAuthCredentialsException.ERROR_REASON);
```
just return null, so skip the compare.

Sorry about that I carelessly apply my own code formatter before pushing, and i have to push another commit to fix the format, not know if this is the right way to do in git, hope not in a mess.