tagging version 2.9.0

git-svn-id: https://plugins.svn.wordpress.org/device-theme-switcher/trunk@1048219 b8457f37-d9ea-0310-8a92-e5e31aec5664
Tagging version 2.9.0

git-svn-id: https://plugins.svn.wordpress.org/device-theme-switcher/trunk@1048224 b8457f37-d9ea-0310-8a92-e5e31aec5664