XML Validation of subsystems

add JBossEntityResolver to resolve imported schema

* XML validation of remoting and threads subsystem
* logging XML can not be validated due to the use of @@ placeholders (the XML validation does not take into account any supplement's replacement)

The pending commits for the wildfly project are at https://github.com/jmesnil/wildfly/commits/xsd_validation_subsystems. I'll open a PR for wildfly with them once wildfly-core 1.0.0.ALPHA15 is released (as some subsystem requires to resolve imported schema)  to be validated).
same here, it should be done by convention by default. no need to explicitly define it, we know where templates are.
OTOH, default templates usually don't ship much of the config and as such don't provide much point in testing as same thing is tested later in manual mode tests where whole standalone.xml is tested.
Here we should test some thing more than just template it should be subsystem config with as much config options defined as possible.