Update Readme

git-svn-id: https://plugins.svn.wordpress.org/wp-pro-quiz/trunk@975739 b8457f37-d9ea-0310-8a92-e5e31aec5664
Update Donate text and links

git-svn-id: https://plugins.svn.wordpress.org/wp-pro-quiz/trunk@975740 b8457f37-d9ea-0310-8a92-e5e31aec5664
Bugfix in Quiz-Complete function

git-svn-id: https://plugins.svn.wordpress.org/wp-pro-quiz/trunk@975741 b8457f37-d9ea-0310-8a92-e5e31aec5664