add controllers/logout shared example
remove logout spec from admins_spec

- use logout shared example in admins_spec instead of a regular spec
re-structure endpoints
- planning to do more re-structuring for almost everything
- one goal is to separate some functionality as components
re-structure almost everything

- if you are looking for a bug then you may well have arrived -_-
- remove Admin model and add Admin::Account instead for better maintainance
- fix(shared specs) make them require that the default factory be provided
  explicitly instead of inferring it from other parameters
- adapt Loginable concern to the new Admin::Account model (Admin model successor)
- migrate the DB to reflect the new changes

stay tuned for more re-structuring (-:
make schema.rb add appropriate indexes
re-structure modules and classes
re-structure modules and classes
re-structure modules and classes
refactor
re-structure modules and classes
re-structure modules and classes
re-structure modules and classes
refactor
refactor