add uniqueness validation in spree preference
return 204 for PUT /orders/empty
Fix spec for ruby 2.0

With Ruby 2.0.0 p451 this was giving:

    expected: 95.17
         got: #<BigDecimal: 95.17000000000001>
Add roadmap url. Fixes #5025
Merge pull request #5032 from HoyaBoya/fix/empty_order_204_response

return 204 for PUT /orders/empty
allow specifying Kaminari page_method_name

only define custom page method if page_method_name != page to avoid recursion
Fixes #5035
Use the proper flash

This is not a success
Fixes #5034
Update Google Analytics

Updates GA tracking code to support Display Advertising. See: https://support.google.com/analytics/answer/2444872 for more.
Fixes #5030
Fix order merging. Fixes #5028
Merge pull request #4999 from vinsol/preference_validation

add uniqueness validation in spree preference
Wait ajax request a bit for backend spec fix
State machine for return_items.

Fixes #5041