Readme with Markdown

git-svn-id: https://plugins.svn.wordpress.org/dailymotion/trunk@968976 b8457f37-d9ea-0310-8a92-e5e31aec5664
Readme markdown 1.5

git-svn-id: https://plugins.svn.wordpress.org/dailymotion/trunk@968979 b8457f37-d9ea-0310-8a92-e5e31aec5664