Run BP_Core_User results through wp_parse_id_list before test assertions

The return values of some BP_Core_User methods are string-cast integers, which
can cause problems when comparing with true integer arrays using assertEquals().

git-svn-id: https://buddypress.svn.wordpress.org/trunk@7032 cdf35c40-ae34-48e0-9cc9-0c9da1808c22