updated md slide separator regex #929

see hakimel/reveal.js#929 (comment)

plugin/markdown/markdown.js

@@ -26,7 +26,7 @@
 		});
 	}
 
-	var DEFAULT_SLIDE_SEPARATOR = '^\n---\n$',
+	var DEFAULT_SLIDE_SEPARATOR = '^\r?\n---\r?\n$',
 		DEFAULT_NOTES_SEPARATOR = 'note:',
 		DEFAULT_ELEMENT_ATTRIBUTES_SEPARATOR = '\\\.element\\\s*?(.+?)$',
 		DEFAULT_SLIDE_ATTRIBUTES_SEPARATOR = '\\\.slide:\\\s*?(\\\S.+?)$';