new parameter "pluginname" pass in the name of your plugin and it shows download info for only that plugin; code optimizations; use 'uid' or 'userid' as the wordpress.org userid parameter name; default cache time changed to 12 hours (43200 seconds); minor code fix

git-svn-id: https://plugins.svn.wordpress.org/wp-plugin-repo-stats/trunk@919902 b8457f37-d9ea-0310-8a92-e5e31aec5664