Bump up version for v3.0.2 for release,
Add compatibility for Easy Digital Downloads plugin,
Remove PHP4 compatible code,
Move changelog to HISTORY.md,
Change the case of readme file,
Fixed changelog format

git-svn-id: https://plugins.svn.wordpress.org/easy-retweet/trunk@935105 b8457f37-d9ea-0310-8a92-e5e31aec5664