Add ServiceLoader support for the ContentItemFactory

By adding the required property file to the META-INF/services directory this will allow to instantiate a ContentItemFactory instance by using the Java ServiceLoader utility

Example code snippet:

private ContentITemFactory contentItemFactory;

public ContentItemFactory getContentItemFactory(){
if(contentItemFactory == null){
ServiceLoader<ContentItemFactory> loader = ServiceLoader.load(ContentItemFactory.class);
Iterator<ContentItemFactory> cifIt = loader.iterator();
if(cifIt.hasNext())

{ contentItemFactory = cifIt.next(); }

else

{ throw new IllegalStateException("No ContentItemFactory Implementation available!"); }

}
return contentItemFactory;
}

Intended to be used when instantiating a ContentItemFactory in the absence of an OSGI environment.