Add filter to wp_login_url() - 'ass_login_url'.

This is so devs can filter where a user can login.
Inject manage member status in the Groups dashboard.

* Uses the new hook in BP 1.8 - 'bp_groups_admin_manage_member_row'.
  Introduces new function - ass_group_admin_manage_member_row().

* Add a second parameter to ass_manage_members_email_status().  The second
  parameter will allow devs to pass the group object.

  Also, add phpDoc and clean up the function.