some cleanup before release


git-svn-id: https://plugins.svn.wordpress.org/ewww-image-optimizer/trunk@932091 b8457f37-d9ea-0310-8a92-e5e31aec5664
tagging and releasing 1.9.2

git-svn-id: https://plugins.svn.wordpress.org/ewww-image-optimizer/trunk@932093 b8457f37-d9ea-0310-8a92-e5e31aec5664
missed a file

git-svn-id: https://plugins.svn.wordpress.org/ewww-image-optimizer/trunk@932095 b8457f37-d9ea-0310-8a92-e5e31aec5664