upgrade to 2.1.0

git-svn-id: https://plugins.svn.wordpress.org/squirrly-seo/trunk@753613 b8457f37-d9ea-0310-8a92-e5e31aec5664
update changelog

git-svn-id: https://plugins.svn.wordpress.org/squirrly-seo/trunk@753614 b8457f37-d9ea-0310-8a92-e5e31aec5664