Timestamps to json give us miliseconds precision

Motivation here was ensure api/orders return updated_at with miliseconds
couldn't find any other easy way to do so. Rails 4 already does it
default
Update all adjustment types

In f9ed99a the order updater was changed to update only shipping
adjustments and promotion adjustments. This was done so that the
in-memory order was used for promotions calculations.

This broke some extensions which expected their custom adjustment types
to receive updates.

This goes back to the previous behaviour of updating all adjustments,
but uses the in memory order object if it is the adjustment's source.

Fixes #3960