ValidationContext using is not correct in UUIDValidator

[qiunju]

json-schema-validator/src/main/java/com/networknt/schema/UUIDValidator.java

Line 36 in cf3b4fe

super(schemaPath, schemaNode, parentSchema, ValidatorTypeCode.DATETIME, validationContext);

Hi, @stevehu
I guess what we want to verify here is UUID, so it should be ValidatorTypeCode.UUID.
I created a PR for it: https://github.com/networknt/json-schema-validator/pull/298/files
Please correct if I'm wrong. Thanks!

[stevehu]

@qiunju Yes. It is a copy/paste error. Thanks a lot for fixing it.