Add tests/types/eui48.rs to excercise MacAddress::parse_str() functionality in canonical form

Author: Andrew Baumhauer

tests/types/eui48.rs

@@ -0,0 +1,9 @@
+extern crate eui48;
+
+use types::test_type;
+
+#[test]
+fn test_eui48_params() {
+    test_type("MACADDR", &[(Some(eui48::MacAddress::parse_str("12-34-56-AB-CD-EF").unwrap()),
+        "'12-34-56-ab-cd-ef'"), (None, "NULL")])
+}