Refactor the way hooks are run

Pulling the hooks into a proper named task class makes it easier
to name the hook while its scheduled in the execution queue, or
for an admin to see what hook might be wedged in the hook queue.

We also get slightly better error reporting.

Change-Id: I8ce82c39d9dbc7c7c4994a1a1419447bf7a4d8c8
Signed-off-by: Shawn O. Pearce <sop@google.com>
1 file changed