Center vertically "+" image in tracker list

src/webui/www/public/css/style.css

@@ -352,3 +352,9 @@ ul.filterList li:hover a {
 	background-color: #e60;
 	color: white;
 }
+
+#addTrackersPlus {
+	width: 16px;
+	cursor: pointer;
+	vertical-align: middle;
+}

src/webui/www/public/prop-trackers.html

@@ -2,7 +2,7 @@
             <table class="torrentTable" cellpadding="0" cellspacing="0" style="width: 100%">
                     <thead>
                             <tr>
-                                    <th>_(URL) <img src="theme/list-add" id="addTrackersPlus" style="width:16px;cursor:pointer;"/></th>
+                                    <th>_(URL) <img src="theme/list-add" id="addTrackersPlus"/></th>
                                     <th>_(Status)</th>
                                     <th>_(Peers)</th>
                                     <th>_(Message)</th>