Upgrade select2-rails to 4.0

[przemosk]

TODO:

• deal with removing last element i.e products in promotions form
• after refresh on customer step in admin checkout values from fields are hidden by clear_address_fields() js function, check why
• css styles

[squash-labs]

Manage this branch in Squash

Test this branch here: https://spark-solutionsupgrade-select2-t55g2.squash.io

[MatthewKennedy]

@przemosk I tried to update select2 to v4 -> https://github.com/MatthewKennedy/spree/tree/select2-v4

I remember battling away with this, I think I fixed it in the end. see if the js from tis file helps with the address fields. https://github.com/MatthewKennedy/spree/blob/select2-v4/backend/app/assets/javascripts/spree/backend/checkouts/edit.js

[przemosk]

@przemosk I tried to update select2 to v4 -> https://github.com/MatthewKennedy/spree/tree/select2-v4

I remember battling away with this, I think I fixed it in the end. see if the js from tis file helps with the address fields. https://github.com/MatthewKennedy/spree/blob/select2-v4/backend/app/assets/javascripts/spree/backend/checkouts/edit.js

@MatthewKennedy will take a look, thanks ! 😄

[MatthewKennedy]

@przemosk You may need to use some of the view files here is the js relies on a change in those:
https://github.com/MatthewKennedy/spree/tree/select2-v4/backend/app/views/spree/admin/orders/customer_details

Pick through the changes and see if there is anything in there that is helpful.

[poudelprakash]

Is this comment still required?

[damianlegawiec]

@poudelprakash nah, can be removed, feel free to submit a PR with this change