Filters

Moved all code that deals with filters into separate module.

class Filter implements  filter methods and returns FilterItem as a result.
FilterItem represent applied filter, remove or pin methods are attached to this object.
PageObject for Pages with filter features should include Filter class via property as usual.

Updated all tests and all pages to those changes.

All tests passed in Firefox.
Bunch tests failed in Chrome, but failures are not linked to refactoring of filters.