template tags: fix get subscribers bug

git-svn-id: https://plugins.svn.wordpress.org/feedly-insight/trunk@853733 b8457f37-d9ea-0310-8a92-e5e31aec5664
0.6.3 bump

git-svn-id: https://plugins.svn.wordpress.org/feedly-insight/trunk@853734 b8457f37-d9ea-0310-8a92-e5e31aec5664