release 3.1

git-svn-id: https://plugins.svn.wordpress.org/bootstrap-shortcodes/trunk@1033643 b8457f37-d9ea-0310-8a92-e5e31aec5664
change version to 3.1

git-svn-id: https://plugins.svn.wordpress.org/bootstrap-shortcodes/trunk@1033653 b8457f37-d9ea-0310-8a92-e5e31aec5664