Add additional unit tests for BP_User_Query.

* test_bp_user_query_include_on_user_page() - tests using only the 'include' parameter with BP_User_Query
* test_bp_user_query_friendship_requests() - emulates the 'Friends > Requests' page

See #4938.

git-svn-id: https://buddypress.svn.wordpress.org/trunk@6939 cdf35c40-ae34-48e0-9cc9-0c9da1808c22