Add changelog, move back to tagged versioning, tag 0.4

git-svn-id: https://plugins.svn.wordpress.org/movabletype-importer/trunk@893852 b8457f37-d9ea-0310-8a92-e5e31aec5664
Fix readme 

git-svn-id: https://plugins.svn.wordpress.org/movabletype-importer/trunk@893854 b8457f37-d9ea-0310-8a92-e5e31aec5664