* Fixed security vulnerability.
* API changed. Method addEmail now responds with "409 Conflict" HTTP code if subscriber already exists.
* Added request parameter "bepositive" to force "200 Ok" HTTP codes on all API responses.
* Added Dutch translation

git-svn-id: https://plugins.svn.wordpress.org/wpnewsman-newsletters/trunk@1015230 b8457f37-d9ea-0310-8a92-e5e31aec5664