add global flag back in for whitespace removal, without it most of the content...

add global flag back in for whitespace removal, without it most of the content in example.html does not work #682

plugin/markdown/example.html

@@ -7,7 +7,7 @@
 		<title>reveal.js - Markdown Demo</title>
 
 		<link rel="stylesheet" href="../../css/reveal.css">
-		<link rel="stylesheet" href="../../css/theme/default.css" id="theme">
+		<link rel="stylesheet" href="../../css/theme/white.css" id="theme">
 
         <link rel="stylesheet" href="../../lib/css/zenburn.css">
 	</head>

plugin/markdown/markdown.js

@@ -50,7 +50,7 @@
 			text = text.replace( new RegExp('\\n?\\t{' + leadingTabs + '}','g'), '\n' );
 		}
 		else if( leadingWs > 1 ) {
-			text = text.replace( new RegExp('\\n? {' + leadingWs + '}'), '\n' );
+			text = text.replace( new RegExp('\\n? {' + leadingWs + '}', 'g'), '\n' );
 		}
 
 		return text;