keep old userid if it is there

git-svn-id: https://plugins.svn.wordpress.org/simple-instagram-widget/trunk@899049 b8457f37-d9ea-0310-8a92-e5e31aec5664
allow usage of username instead of userID - tagging 1.1.1

git-svn-id: https://plugins.svn.wordpress.org/simple-instagram-widget/trunk@899057 b8457f37-d9ea-0310-8a92-e5e31aec5664