Log CVV response messages on payments

Fixes #3266
fix hardcoded paths for fontawesome

Fixes #3248
Fixing the problem with translate with relative path.

This commit fix #3176 and add #translate method to Spree module.

To fix this issue, was necessary adding a monkey patch to initialize
the i18n after load the spree base controller.

Also, I changed the method #t. Now this method is an alias to #translate.

In my concept, we need to follow the same convention of i18n and
translation helpers of rails.

So, the developers can use #t and #translate without any problems.

Fixes #3257
Fixes #3176
Not all promotions respond_to :products

Fixes #3265
Fixes #3261
[frontend] Really check for flash[:error] in orders_controller_spec, rather than setting it

Fixes #3259
[frontend] Shipping rates should use Spree::Money, not number_to_currency, to display correct amounts on delivery screen

Fixes #3246
[frontend] Shipping rates should use Spree::Money, not number_to_currency, to display correct amounts on delivery screen

Fixes #3246
Add alias for display_price to display_cost for ShippingRate