Add all primary models, scaffolds, controllers -- pre-migration

* Article scaffold
* User scaffold
* SiteProfile scaffold
* Content controller
* Comment model
* ArticleC12n model
* SecurityLevel model
* Tag model
* Categorization model
Migrated for all pivotal data models

* Migration results (schema)
* Inconsequential:  rename/delete application.css to .css.scss
* Inconsequential:  fixed site_profiles.yml fixture