Remove Google+ shared link button because the Google+ service has ended #136
This pull request removes "Google+" from the article share button.
The Google+ service ended in April 2019. Therefore, it is necessary to delete it from the share button of the article.
Currently, when Google + 's share button is clicked, the Google+ end announcement page is displayed. Therefore, this button will not be used. So pull request for deletion.
e.g. URL of Google+ share from the demo site of this theme