feat: basic implementation of crud plugin
refactor: fix minor coding standard issue
feat: enable Crud to catch MissingActionException and attempt to generate response using Crud.
feat: migrate categories to crud
feat: implement a units model/db to replace the enumerable behavior that was previously used
feat: migrate remaining controllers to Crud
refactor: correct code standards
Merge branch 'feature/implement-crud' into develop
feat: make flash messages dismissible, and colored according to message type (success, failure or info)
feat: move to CakeDC Users plugin for users, revise security and implement a landing page