ADD: Categories seed
ADD: Categories Controller & route
ADD: Category model
ADD: Categories to seeder
MOD: Cleaned up Products
MOD: update db with categories
MOD: cleaned up REST-API
MOD: fixed some REST description
ADD: Products Routes with category handling
ADD: Seeder for category
ADD: Migration for category
MOD: deactivate write to categories (not tested yet)
MOD: Deactivated writes add categories filter
ADD: Route for categories
FIX: full handling of products
ADD: Relation between Products and categories
ADD: ember category model
DEL: get rid of products model
MOD: defined controllers
MOD: cleaned old code
MOD: fixed products and categories