Trying to get a collection of concurrent adjustments in promo action

So we can check which one has the highest adjustment and then decide if
the promotion linked to the promo action can be eligible
Grabs promotions through adjustments in a proper way
Improves query to get products through line items in Order
Removes confusing method from promo order decorator

Let the main app worries about it right now. The alias_method_chain
seems to break when we need to override the method somewhere else
Implements interface for eligibility based on best concurrent discounts

Looks like it's working great, however no specs written, shame on me,
and no tests through their interface
Improves products method in Spree::Promotion

It should collect products in all Rules that respond to a product
method. This can take the api to a whole new level of flexibility
Removes eligibility concern from adjustment#update!

Adjustments eligibility should be check only after all adjustments are
updated on the current order. For now we will stick with the
order#update_adjustments_with_promotion_limiting to define promotions
adjustments eligibility
Makes sure concurrent discounts is always a number
Fixes adjustments association on CreateAdjustment
Adds only adjustments from eligible promotions to concurrent discounts
Boost products query from order object

The previous version would make an add to cart event take like:

  /store/orders/populate/     14985ms

After this change:

  /store/orders/populate/     756ms
  /store/orders/populate/     1222ms
  /store/orders/populate/     584ms

There is still too much query stuff associated with promotion stuff. It
should be worth taking a look to improve the database structure or cache
some of the results
Updates doc blocks and try to make code more readable

The first time an user adds an item is still extremely slow. Taking
about 7s.
Lists only eligible adjustments in admin order view
Don't clear mail_method or payment_method password if it's not sent through with params

Fixes #2094
Hides ship address when page loads and use bill address is checked
Just call render when admin updates customer details

The #update in Admin::Orders::CustomerDetails set a shipping method for
that order but I have no idea why. It doesn't make much sense