clean up
updates: Gem files to user rails 4, spree 2.3
updates: asset structure for spree 2.3
updates: models for spree 2.3 and rails 4
updates: models for spree 2.3 and rails 4
updates: routes for  spree 2.3
updates: generator for spree 2.3
updates: gemspec, use rails4, rpsec3, spree 2.3
updates: spec_helper for rspec 3
adds: rails_helper in the specs for rspec 3