Always create assets in test env `rake test_app`

Build in extensions broke because Spree::Frontend and Spree::Backend are
not defined when running `rake test_app` within extension gem context

Fixes #3441
Dont require capybara helpers in core spec. Fixes #3442
Remove paperclip matchers not used in core specs.
Remove dash specs that were accidentally added during capybara 2 upgrade.
Remove unused routes. Fixes #3443
Selects 'state' as default zone type when there has not yet been a selection made.  We are already showing the 'add state' button in this case, so this commit makes the UI uniform ('state' radio is selected and 'add state' button is shown)

Fixes #3432
Add option_values to variant template [api]

Fixes #3460

Conflicts:
	api/app/views/spree/api/variants/variant.v1.rabl
	api/spec/controllers/spree/api/states_controller_spec.rb