change require statement "spree_core/testing_support/common_rake" to "spree/testing_support/common_rake" in Rakefile
In rake task test_app (Add mysql in ENV[db], change env LIB_NAME to "spree-point-of-sale)"
change gemspec file to "spree-point-of-sale.gemspec" in Rakefile
Change spec load path to use dummy app
Add initializer spree.rb with "extend ActionView::Helpers::TagHelper" in module Spree for fixing content_tag bug
Add spec/dummy in .gitignore