[in-commerce] Shipping quote engine small refactoring

Imported from: http://groups.google.com/group/in-portal-dev/browse_thread/thread/d7a4deac132f92ba#

I've changed shipping quote engine integration a little bit, so it's now easier to add new shipping quote engines.

Only thing, that left is display different editing template, for each of shipping quote engines.

Please test that as soon as possible and maybe we can even place it in 5.1.0 release.

shipping_engine_system_small_refactoring.patch

Related Tasks

MINC-60 - Getting issue details... STATUS