Refactor extract SimpleTokenAuthenticatable inclusion to method

`SimpleTokenAuthentication` is responsible for including
its `ActsAsTokenauthenticatable` module into the models base class;
and does so through :ensure_models_can_act_as_token_authenticatables
Add SimpleTokenAuthentication::Configuration specs
Refactor Configuration specs

Add configuration option interface specs (private)

Minor fix misspelling in dummy classes documentation
Minor fix misspelling in ActsAsTokenAuthenticationHandler specs
Refactor extract ActiveRecordAdapter, inject dependency
Merge branch 'refactor-encapsulate-dependencies-on-active-record'