Ensure that add_user_to_group() params get passed through in testcase.

git-svn-id: https://buddypress.svn.wordpress.org/trunk@7988 cdf35c40-ae34-48e0-9cc9-0c9da1808c22
Insert default values when updating last activity

This prevents errors on certain configs.

Fixes #5424

Props imath

git-svn-id: https://buddypress.svn.wordpress.org/trunk@7989 cdf35c40-ae34-48e0-9cc9-0c9da1808c22