merge from github

git-svn-id: http://plugins.svn.wordpress.org/featured-image-via-url/trunk@826881 b8457f37-d9ea-0310-8a92-e5e31aec5664
update php header.

git-svn-id: http://plugins.svn.wordpress.org/featured-image-via-url/trunk@826884 b8457f37-d9ea-0310-8a92-e5e31aec5664
update compatible version.
Merge branch 'master' of github.com:tsaiid/wp-plugin-featured-image-via-url