Add social media icons to author byline

Optionally add these styles as well:
a.author-social {
margin: 0 0 0 1em;
}
.author-social:hover .fa-facebook {color: #3b5998;}
.author-social:hover .fa-twitter {color: #00aced;}
.author-social:hover .fa-google-plus {color: #dd4b39;}