It uses Gravatar, WordPress by default uses Gravatar images, simply go to gravatar.com and sign up with your email and setup your image, it’s free. Once you have associated an email with picture on gravatar it will start appearing automatically, no plugin is needed.
For Google+ Author:
No plugin is needed, theme has integrated authorship functionality.
To configure Google+ Author fill out the profile fields in Users -> see screenshot
After this link your website/author page from your Google+ page and your picture will start appearing in search after a few hours.