api: add sinatra-contrib gem
api: add production database config
api: make app runnable in different modes
api: update all table indexes
api: clean BaseController
api: add Collection to models
api: exclude BaseController, use Application instead
api: use sinatra/contrib helpers and extensions
api: use ErrorHandling extension
api: refactor application configs
api: expect and parse JSON input for POST and PUT requests
api: add POST /collections implementation
api: refactor GET /collections/:id