rename markdown attribute test files to same format

Author: hakimel

test/test-markdown-attributes.html renamed to test/test-markdown-slide-attributes.html

@@ -122,7 +122,7 @@
 		<script src="../plugin/markdown/markdown.js"></script>
 		<script src="qunit-1.12.0.js"></script>
 
-		<script src="test-markdown-attributes.js"></script>
+		<script src="test-markdown-slide-attributes.js"></script>
 
 	</body>
 </html>