Remove the bulk of SSL handling code in favor of default Rails "force_ssl" config option

Conflicts:
	core/lib/spree/core/ssl_requirement.rb
Process processable payments as soon as possible outside any transaction
Fix route in Admin::PaymentsController
Pagination of Orders in Admin loses date range when only showing complete orders

As date params are deleted if @show_only_completed is true,
store the original date so we can restore them into the params
after the search

[Fixes #1724]
Remove deprecated ssl_required and ssl_allowed
Use user_search_basic for user auto-completion