removed unreachable tokeInfo error check block.

The following ` if (tokenInfo.containsKey("error"))` in Verify.java is unreachable and slightly misleading. Because when calling

    Tokeninfo tokenInfo = oauth2.tokeninfo().setAccessToken(accessToken).execute()

With an invalid token (such as an expired one), the SDK will always throw an Exception instead of returning a Tokeinfo object:

    com.google.api.client.googleapis.json.GoogleJsonResponseException: 400 Bad Request
        at com.google.api.client.googleapis.json.GoogleJsonResponseException.from(GoogleJsonResponseException.java:145)

The `GoogleJsonResponseException` is quite understandable. You can verify by calling the API directly without using the SDK: `https://www.googleapis.com/oauth2/v1/tokeninfo?access_token=`. If a invalid/expired token is used, the error response can't be parsed into a Tokeninfo object:

    {
        error: "invalid_token",
        error_description: "Invalid Value"
    }

Therefore the developer really shouldn't be checking for errors in the Tokeninfo but instead rely the IOException catch block.