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
Replaced Taxon :position refs with :child_index=

Fixes #3390
Fixes #3956

Taxon position unnecessarily fights against the awesome_nested_set
API. By using a_n_s's :move_to_child_with_index method we can more
fully leverage acts_as_nested_set.
Not attempting to reorder taxon on create since awesome_nested_set refuses
Bump to activemerchant 1.42.2

Conflicts:
	core/spree_core.gemspec