Use class="code" for <code> in HTML generated from Markdown

This is necessary for proper formatting of backtick-delimited `inline
code`. The HTML for ```fenced code blocks``` was already being emitted
with this attribute, causing inconsistent application of typefaces
between the two forms of code in Markdown.

Bug: issue 127
Change-Id: Ia1a9e7bf00c994a96278abeb6847426523c87d05

gitiles-servlet/src/main/java/com/google/gitiles/doc/MarkdownToHtml.java

diff --git a/gitiles-servlet/src/main/java/com/google/gitiles/doc/MarkdownToHtml.java b/gitiles-servlet/src/main/java/com/google/gitiles/doc/MarkdownToHtml.java
index f734949..99f1c53 100644
--- a/gitiles-servlet/src/main/java/com/google/gitiles/doc/MarkdownToHtml.java
+++ b/gitiles-servlet/src/main/java/com/google/gitiles/doc/MarkdownToHtml.java
@@ -334,7 +334,7 @@
 
   @Override
   public void visit(Code node) {
-    html.open("code").appendAndEscape(node.getLiteral()).close("code");
+    html.open("code").attribute("class", "code").appendAndEscape(node.getLiteral()).close("code");
   }
 
   @Override