csv generating in model

after much overthinking I decided to go with basic
and upgrade after making it work
in meantime, rake:export does not work for me
localy, so checking that out too
generating csv string in relic model

and then save it in zip in rake task
modified rake task not to duplicate the same code
modified pages/download default
Merge branch 'feature/454-csv-for-downloads' into next

Conflicts:
	app/controllers/relics_controller.rb
	config/locales/pl.yml