Extract CSS styles from milestones.scala.html.

src/main/webapp/assets/common/css/gitbucket.css

@@ -70,6 +70,11 @@ a.omit:hover {
   background-color: #aaa;
 }
 
+span.count-right {
+  float: right;
+  font-weight: bold;
+}
+
 .monospace {
   font-family: monospace;
 }