support for data-markdown (#15)

lib/js/data-markdown.js

@@ -0,0 +1,19 @@
+// From https://gist.github.com/1343518, modified to not load showdown
+(function boom(){
+
+  [].forEach.call( document.querySelectorAll('[data-markdown]'), function  fn(elem){
+      
+    // strip leading whitespace so it isn't evaluated as code
+    var text      = elem.innerHTML.replace(/\n\s*\n/g,'\n'),
+        // set indentation level so your markdown can be indented within your HTML
+        leadingws = text.match(/^\n?(\s*)/)[1].length,
+        regex     = new RegExp('\\n?\\s{' + leadingws + '}','g'),
+        md        = text.replace(regex,'\n'),
+        html      = (new Showdown.converter()).makeHtml(md);
+
+    // here, have sum HTML
+    elem.innerHTML = html;
+
+  });
+
+}());