[CORE-3568] Filter options for client widgets - Blesta

Details

Each widget on the client profile should be updated to support filters. This applies to both the client and admin interface.

Each widget controller method should handle filtering form submission
Each widget controller should handle creating an InputFields object with the appropriate filtering fields (perhaps these should be handled by the model? Or helper classes? Core classes?)
Each widget should use the ajax submission option (AbstractMethod::setAjaxFiltering())
Make sure each filtering form is hidden on initial load, but shown after submission
Models may need to be updated to support this level of filtering
Pagination and sorting should still function properly (submitting filters can reset pagination and filters)