Made address validation more obvious

When validating an address field any errors produced will be attributed
to either billing or shipping information. This is intended to cleanup
any confusion there may be for users thinking they have completed fields
they haven't.
Products & best sellers plugin update
Merge branch '1.2/develop' of https://github.com/firesale/firesale into 1.2/develop
Added a new method to retrieve cart contents as a json object
Merge pull request #362 from superrbstudio/1.2/develop

Added a new method to retrieve cart contents as a json object
Fixed shipping price/weight checks
Updated shipping admin view
Updated get shipping methods
Some italian update

Here some update for the FireSale Modules, I need other time to check
some strings.
Sorry for the delay :)
As always, I prefer you to merge my request ;)
Merge pull request #363 from ChristianGiupponi/1.2/develop

Some italian update
Added minimal to complete, fixed price issue
Fixed inserting variations into the cart directly
Fixed route create/edit redirect issues
Small formatting update
Stop modifier check when variation added to cart
Cache currency in cart plugin
Attributes now only shown during product edit
Added addresses plugin
Added orders plugin
Fixed quickedit bug, closes #360