def define_and_assign_attr_accessors_for_each_filter(fp)
      model_class.filterrific_available_filters.each do |filter_name|
        self.class.send(:attr_accessor, filter_name)
        v = fp[filter_name]
        self.send("#{ filter_name }=", v)  if v.present?
      end
    end
def define_and_assign_attr_accessors_for_each_filter(fp)
      model_class.filterrific_available_filters.each do |filter_name|
        self.class.send(:attr_accessor, filter_name)
        v = fp[filter_name]
        self.send("#{ filter_name }=", v)  if v.present?
      end
    end
Defines attr accessors for each available_filter on self and assigns
 values based on fp.
 @param fp [Hash] filterrific_params with stringified keys