option cleaning after uninstall

git-svn-id: https://plugins.svn.wordpress.org/instantsearch-for-woocommerce/trunk@995379 b8457f37-d9ea-0310-8a92-e5e31aec5664
release 1.2.7

git-svn-id: https://plugins.svn.wordpress.org/instantsearch-for-woocommerce/trunk@995381 b8457f37-d9ea-0310-8a92-e5e31aec5664