Hotfix for bbPress activity ID fetching.

Changes to BuddyPress in v2.1 to remove the activity count from activity
queries broke how bbPress determines what the existing activity ID is.

This is a hotfix to add the new 'count_total' parameter added in BP 2.1, so
bbPress can accurately fetch the correct activity ID.  This prevents
duplicate activity entries when editing a bbPress forum post.

This should hopefully be addressed in bbPress 2.6. Remove this in CBOX 1.1.

See https://bbpress.trac.wordpress.org/ticket/2690

See #103.