Fix an incorrect inverse_of

This breaks things in strange ways...
AdjustmentSource tests moved into a shared example.

has_many and before_destroy declarations moved into concern.

fixes #5731
Fixes to run tests in windows.

http://stackoverflow.com/questions/23022258/tzinfodatasourcenotfound-error-starting-rails-v4-1-0-server-on-windows

http://stackoverflow.com/questions/10154670/system-cannot-find-the-path-specified-when-running-rake-test-app-with-spree

Fixes #5734
Merge pull request #5747 from gmacdougall/fix-bad-inverse

Fix an incorrect inverse_of
Eager load associations in InventoryUnitBuilder

Everything here will be needed inside coordinator, perhaps we could have
some sort of `assert_no_queries` examples on the build to see whether
and when we miss any records

fixes #5690
Improved no_state_changes message

And moved it to the bottom of the code (like other pages)

Added logged-in and out classes to header

Changed way of defining an admin user

Added some styles for logged out header

fixes #5743
Simplify a couple specs.
Fix the styling of the state field on the stock location admin page +

The form-control class is missing from the text input, which is
activated when the selected country has no states.
New CircleCI badge!

fixes #5751
Update order tabs data-hooks to reflect the state
fixes #5750
ItemAdjustments refactored

Remove callbacks from ItemAdjustments

It is unclear what the benefit of the callbacks were here. They're not
demarking a change of state or something complex. They're just
for inserting into the middle of a fairly short sequence of actions.
With it broken into smaller methods, it's now fairly easy to override
one of the methods and call super in a sub-class.

Renamed ItemAdjustments as Adjustable::AdjustmentsUpdater

This is a method object, not a model, so its more consistant to place
it in a subfolder. It also doesn't operate an "Item" model, but on any
of the models that fall under the "Adjustable" association.

Propagate ItemAdjustment name change

Add note to changelog

Closes #5739
Promotion actions refactored

Make adjustments on LineItem not Order

Closes #5738
remove merge conflict that was still there.
the Spree::ItemAdjustments model is no longer here,
commented out the shared examples in the specs for now.
fix typo in promotion policy select
get the currency on the package from the order.

fixes #5746
closes #5753
Fix for failure of one of multiple payments.

This corrects an issue which would leave the user on the confirm page
when one of multiple payments failed. This would allow the user to
proceed through the confirm step with an invalid payment, not billing
them for the full amount required.

An example would be with the store credit payment method, where they are
able to pay for part of the order with store credit. Example, the
customer has $20 store credit available and is trying to purchase a $100
item.

Currently, if attempting to charge $80 to the credit card fails (due to
the card being declined), they $80 credit card payment will be flagged
invalid, leaving only the $20 payment. The user would remain on the
confirm page, which allows them to check out paying $20 on their store
credit. The user will beleieve that everything worked correctly, however
their $20 store credit has been consumed, but the order is still in a
balance due state.

This is fixed by only allowing an order to remain on the confirm page if
they have sufficient payments to pay for the entire order.

Closes #5754