Added validations for less_than and greater_than

validate_greater_than(param_name, param, compare)
validate_greater_than_or_equal_to(param_name, param, compare)

validate_less_than(param_name, param, compare)
validate_less_than_or_equal_to(param_name, param, compare)

Couldn't find any tests that actually test if the validations work like expected. I think we should add this to the test suite soon!