added support for ignoredClasses

It is currently possible to specify additional resources on the classpath that are excluded from the duplication check (Globally ignoring additional resources).

Sometimes it's also interesting to exclude certain classes on a global level (without specifying in what dependency they are defined).

This pull request also allows you to do the same with classes on a global level by adding an ```ignoredClasses``` element to the configuration.

```
       <ignoredResources>
           	<resource>META-INF/.*</resource>
		</ignoredResources>
		
       <ignoredClasses>
           <class>be\.ecs\..*</class>
           <class>org\.apache\..*</class>
       </ignoredClasses>
```