Add class to bookmark links to make it better them able

E.g.: css (not yet included)
.bookmark-identifier{
display:none;
}
.bookmark:hover:before{
text-decoration:none;
content:"#^";
color:#000000;
background:#FFFFFF;
}

.bookmark:hover{
	color: #FFFFFF;
	background: #3465A4;
}
.
Merge pull request #306 from cvogeley/master

Add class to bookmark links to make it better themable