update changelog and prepare for 1.3

git-svn-id: https://plugins.svn.wordpress.org/indeed-apply-shortcode/trunk@893875 b8457f37-d9ea-0310-8a92-e5e31aec5664
updating stable tag to 1.3

git-svn-id: https://plugins.svn.wordpress.org/indeed-apply-shortcode/trunk@893877 b8457f37-d9ea-0310-8a92-e5e31aec5664