udpate dependency on spree_core to be ~>2.1.0 and gem version
update to use shipments.last instead of shipment for access to shipment, remove attr_accessible for upgrade to rails4, update routes format, update specs for the changes, update spree version in Gemfile, update to use permitted_params for stock_location_controller#update
update routes format and override for pos_tab
require jquery tab for pos page
two todos added
gemspec and README changed
resolve README conflicts after merging upgrade_2.1 branch in master