Add missing ORM specs and fix bugs discovered

[pboling]

Fixed

• [ActiveRecord] Fixed #110 which prevented OmniAuth::Identity::Models::ActiveRecord-based records from saving.
• [CouchPotato] Fixed OmniAuth::Identity::Models::CouchPotato's #save.
• [Sequel] Fixed OmniAuth::Identity::Models::Sequel's #save.
• [Model] Only define ::create, #save, and #persisted? when not already defined.
• [Model] Restore original info functionality which set name based on first_name, last_name, or nickname

Changed

• Upgraded to a newer OmniAuth::Identity::SecurePassword ripped from Rails 6-1-stable
  • Aeons ago the original was ripped from Rails 3.1, and frozen in time.
    While writing specs, it was discovered to be incompatible with this gem's Sequel adapter.
  • Specs validate that the new version does work.
    In any case, the ripped version is only used when the has_secure_password macro is not yet defined in the class.

Added

• New specs to cover real use cases and implementations of each ORM model adapter that ships with the gem:
  • ActiveRecord (Polyglot - Many Relational Databases)
  • Sequel (Polyglot - Many Relational Databases)
  • CouchPotato (CouchDB)
  • Mongoid (MongoDB)
  • NoBrainer (RethinkDB)

CC @nbibler

[nbibler]

Wow, quite a rabbit hole here! Thank you for looking into it and fixing these problems, @pboling! ❤️