Use 'save_post' hook to bust directory_pages cache

The save_post_{$post_type} hook did not exist until a recent version of
WordPress.

git-svn-id: https://buddypress.svn.wordpress.org/trunk@7821 cdf35c40-ae34-48e0-9cc9-0c9da1808c22
Use specific users when creating activity items in test suite

git-svn-id: https://buddypress.svn.wordpress.org/trunk@7822 cdf35c40-ae34-48e0-9cc9-0c9da1808c22