Fix .thumbnail line-height

Created by: Nivl

less/thumbnails.less

@@ -27,7 +27,7 @@
 .thumbnail {
   display: block;
   padding: 4px;
-  line-height: 20px;
+  line-height: @baseLineHeight;
   border: 1px solid #ddd;
   .border-radius(4px);
   .box-shadow(0 1px 3px rgba(0,0,0,.055));