fixes #5634 - save sso_method on session expiry

fixes #5773 - redirect to referrer URL that includes page and search

fixes #7586, #7734, #7172 - user preferences for receiving mail notifications

Adds a framework for user-selectable mail notifications. The work is
still done in ActionMailer classes and launch by rake in cron, however a
wrapper called MailNotification is used to provide RBAC and make the...

fixes #3492 - API v2 nested routes for each controller

Refs #3809 - Use parentheses in method definitions

Refs #3809 - Fix a few rubocop TODOs

Refs #3809 - Remove rubocop TODOs

Removed the following TODOs so that cops for these will run from now on:

Lint/AmbiguousOperator, DefEndAlignment, DeprecatedClassMethods
EnsureReturn, RequireParentheses, Void, BlockAlignment, EndAlignment,
UselessAccessModifier,...

fixes #4386 - gem friendly_id to simplify find by id, name, label, etc

fixes #7253 - change nil admin field on users to false, matches usergroups

When the admin field was nil, admin_changed? in user model validations can
evaluate to true if the field changed from nil to false.

Fixes #6763 - Correctly choose autocomplete search scope for taxonomies depenant on controller