def valid_filter_value(key, value)
			return true if value.nil?
			return true if solve_filter_value(key, value)
		end
def valid_filter_value(key, value)
			return true if value.nil?
			return true if solve_filter_value(key, value)
		end
Internal : Validates a specific filter criteria and his value

 Author:: jlopezn@neonline.cl

 key - filter criteria to evaluate
 value - filter criteria to be evaluate

 Returns:: true if validation runs ok. Raise exception otherwise

 Raises:: Exception if filter value provided is not valid