Remove X-UA-Compatible from layout

Fixes #2152

Fixes #2151
[api] Tidy up parameters in zones_controller_spec
Fixing Jirafe Links, Fixes #2144

Fixes #2150
Remove ShippingMethod#calculator_available?

Related to #2149
Even more admin fixes!

* Replace static values with variables in admin stylesheets
* Remove unsude css reset file already. Now we use normalize.css on frontend and backend.
* Fix admin thead th font weight

Fixes #2146
Stripping EXIF from JPGs

Fixes #2142
Fixes #2145
Ensure ALL select2 choices show up in taxons for admin/products/edit

Fixes #2139
[api] Fix zones_controller_spec
'Shipment' is no longer prefixed to the shipment id in shipments edit page
Remove respond_{to/with} calls from controllers that don't need them
Remove un-used @txn_partials setup from Spree::Admin::OrdersController
Admin::PaymentsMethod#update needs respond_with call
OrdersController#update needs respond with to determine order path
[promo] Remove excessive respond_with usage in CheckoutControllerDecorator
Fix import calls to work during extension integration tests.

Fixes #2161
Remove useless event_names tests from activator_spec

Coincidentally: these caused RSpec's --format documentation to crash
Wait until AJAX has completed in configuration/states_spec

Fixes randomly failing builds like this one: https://travis-ci.org/#!/spree/spree/jobs/2995890
Don't class_eval StoreController for each file in promo's decorators
Only include eligible promotions in promo_total
Removes deprecation warning during preferable_spec run

Fixes #2174