Run chef before operations that need it.

Chef, if it is needed, should be run before kernel tasks
and before all other user defined tasks.  It should not be
run by default.

Fixes: 9495
Signed-off-by: Warren Usui <warren.usui@inktank.com>
Merge pull request #333 from ceph/wip-9495-wusui

Run chef before operations that need it.