Apply ng to issue dashboard

public/ng/less/ui/var.less

@@ -45,6 +45,10 @@
 @btnGrayHoverColor: #FAFAFA;
 @btnGrayBorderColor: #D0D0D0;
 
+@btnWhiteColor: #FFF;
+@btnWhiteHoverColor: #e8e8e8;
+@btnWhiteBorderColor: #c6c6c6;
+
 @lineMenuHoverBgColor: #EAEAEA;
 @lineMenuHoverFontColor: #444;