Add a node revisions (and logs) when tasks are executed.
Use task vids in AJAX calls and keep track of status changes between AJAX calls.
Add hook_js() implementation and rename associated functions.
Allow setting both idle and busy AJAX poll timeouts.
Allow getting the queue status for individual nodes.

We add hosting_task_count_status(), which generalizes the counting of
queued items of a given status, and allows for an optional NID. We then
re-use it in hosting_task_count() and hosting_task_count_running(), thus
allowing us to pass an NID into either of these too.
Allow looking up the queue status for an individual node.
Move to the new AJAX mechanism for the hosting queue lists on nodes too.