Fixed bug: PHP error while AdWords remarketing or enhanced ecommerce enabled and the category is empty

git-svn-id: https://plugins.svn.wordpress.org/duracelltomi-google-tag-manager/trunk@975882 b8457f37-d9ea-0310-8a92-e5e31aec5664
Fixed bug: only classic ecommerce was shown on admin tab

git-svn-id: https://plugins.svn.wordpress.org/duracelltomi-google-tag-manager/trunk@975883 b8457f37-d9ea-0310-8a92-e5e31aec5664