Update version 1.0.4

git-svn-id: https://plugins.svn.wordpress.org/delete-multiple-themes/trunk@808092 b8457f37-d9ea-0310-8a92-e5e31aec5664
Fix readme.txt

git-svn-id: https://plugins.svn.wordpress.org/delete-multiple-themes/trunk@808095 b8457f37-d9ea-0310-8a92-e5e31aec5664