Remove append_view_path from api ControllerSetup

That line was preventing us from overriding templates within other
application or extensions

Fixes #3450

Conflicts:
	api/lib/spree/api/controller_setup.rb
Revert "Remove append_view_path from api ControllerSetup"

This reverts commit f4de69f2e9b02a8e4a87b987138c0a659336bfcf.
Add index to Spree::User.spree_api_key

Fixes #3884
fix inline comment that can cause deface errors

see https://github.com/spree/deface/issues/113 for more info
Fix invalid erb comment syntax in admin/taxons/edit.html.erb

Fixes #3926