Correct documentation for title helper

Fixes #2878
Fix user role mass assignment from backend

This was broken by commit 175a23211337c9ba53242b54d19f84642989e984.

This specifically fixes two problems:
- #2905 Mass assignment exception when creating new users through backend
- #2904 Backend user gets logged into edited user account when changing
	password

Also update and unify core/auth admin user specs

- Add core admin create user spec
- Add auth admin create and edit user specs
- Merge badly namespaced auth user_spec into admin/users_spec
[core] Remove page! call in checkout spec
Check last inventory unit checkbox in shipments_spec

This should fix compatibility on postgresql+MySQL
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