HV-837, HV-858

* Making sure the default validator (factory) bean represents the type configured in _META-INF/validation.xml_
* Adding new and cleaning up existing tests

Once [WFLY-2762](https://issues.jboss.org/browse/WFLY-2762) has been resolved and we've updated to use the corresponding WF version, commit https://github.com/gunnarmorling/hibernate-validator/commit/dfa1ed65c3d9171563b5e4f0d73a9449be4fd0fe can be reverted to actually run the concerned tests.