tweak to plugin upgrade to not delete options (yet)

git-svn-id: https://plugins.svn.wordpress.org/worpit-admin-dashboard-plugin/trunk@1041113 b8457f37-d9ea-0310-8a92-e5e31aec5664
version bump to 2.9.2

git-svn-id: https://plugins.svn.wordpress.org/worpit-admin-dashboard-plugin/trunk@1041116 b8457f37-d9ea-0310-8a92-e5e31aec5664