GH-88 Use Injector to initialize extensions

[huyuwen]

Hi Sven and Jan,

I tried to create a Class which implements IValdiationExtension `class MyYangRuleValidator implements IValidatorExtension { @Inject protected extension YangExtensions yangExtesions;

override validate(AbstractModule module, IAcceptor<Issue> issueAcceptor, CancelIndicator cancelIndicator) {
    System.out.println("Invoke test");
}

}`

The Validator class could be loaded, but yangExtensions is still null. Did I do something wrong?