Make possible to load a RunnerFeature dynamically

A feature can depend on other features by annotation them with @Features but this mechanism is static, ie: we can not condition a feature dependency for instance. We have introduce DynamicFeaturesLoader to be able to depend on a feature with a simple programmatic API, for instance MyFeature can now depends on MyOtherFeature depending on some conditions, this is accomplished by created a constructor with a DynamicFeaturesLoader parameter in your feature, see an example below: public class MyFeature implements RunnerFeature { public MyFeature(DynamicFeaturesLoader loader) { if ( Boolean .parseBoolean( System .getProperty( "nuxeo.test.with.other.feature" , " false " ))) { loader.loadFeature(MyOtherFeature.class); } } }