Update v2 api for products controller and routes

These changes include:

- Fixes typos and rubocop offences
- Add more tests and modify existing tests to work with strong_params
- Refactoring and DRY up the code
- Make search work
- Refactor to extract filtering into methods
- Minor change in SystemGroupsController to reuse from base controller
- Fix providers routes, tests, and clean up merge
- Whitespace changes to before_filter in providers controller
- Remove duplicate actions in providers controller
- Fix failing create product test
- Make refresh_manifest send the correct status code

Conflicts:
	app/controllers/katello/api/v2/products_controller.rb
	config/routes/api/v2.rb