Spree::Store now ensures that there always will be a default (even if the developer fails to set one) and that there will be a maximum of 1

Fixes #81
Fix current_order decorator syntax

Since it has changed on latest spree-2-0-0

Conflicts:
	lib/spree_multi_domain/engine.rb
Merge branch '2-1-stable' of https://github.com/jason123456/spree-multi-domain into 2-1-stable
add toxon with store selection