Primer commit branch "probando de todo sin orden". No usar estos commits!

Despues mergearlo en orden y bien.

commit: agrego mejor logueo de request de bitpagos: con puts igual.
payment method: agrego metodos vacios copiados de coinbase-spree.
complete success action.
Fix param posted by BitPagos: reference_id -> referenceId.
branch for spreee 2.3.
update controller.
Fix ruby string interpolation: requires double-quote marks.
hacks para arreglar payments desde el admin.
fix can_void method.
fix for payments wrongly created without shipping cost.
update controller.
Merge branch '2-1-stable' into 2-3-stable
add routes for new checkout organization.
Add discount preference.
Add create_adjustment.
Add translation
Add translation