Add footer and slide numbers to PDF export

Change-Id: I47dd08572ac89be7f06286f4dd18775351fed0de
diff --git a/inst/rmarkdown/templates/revealjs_presentation/resources/default.html b/inst/rmarkdown/templates/revealjs_presentation/resources/default.html
index f23dbe1..9c9ee98 100644
--- a/inst/rmarkdown/templates/revealjs_presentation/resources/default.html
+++ b/inst/rmarkdown/templates/revealjs_presentation/resources/default.html
@@ -678,7 +678,7 @@
     }
 
     function makeFooterAndSlideNumberInvisibleOnTitlePage(event) {
-      if (event.indexh === 0) {
+      if (event.indexh === 0 && ! Reveal.isPrintingPDF()) {
         Reveal.configure({ slideNumber: null });
         makeFooterInvisible();
       } else {