Support 2.1.0.beta
Add Spree.t() and missing translations in the en.yml file

I also changed all Spree.t("a_string_word") to Spree.t(:a_string_word)
except for nested ones eg Spring.t("a_nested.string_word")
fixed plural names
Merge branch '2-0-stable' of github.com:primetimesolutions/spree-multi-domain into 2-0-stable

Conflicts:
	spree_multi_domain.gemspec