Bug 182895 Support sort on Level attribute.
Currently in OLAP engine we only support sort on level key value. We should go ahead to support sort on level attribute value.
data/org.eclipse.birt.data.tests/test/org/eclipse/birt/data/engine/olap/api/CubeFeaturesTest.java
hier1.createLevel( "level12" );
		hier1.createLevel( "level13" );
		IDimensionDefinition dim2 = rowEdge.createDimension( "dimension2" );
		IHierarchyDefinition hier2 = dim2.createHierarchy( "dimension2" );
		ILevelDefinition level21 = hier2.createLevel( "level21" );
		createSortTestBindings( cqd );
		
		CubeFilterDefinition filter1 = new CubeFilterDefinition( new ScriptExpression( "data[\"rowGrandTotal\"] > 420" ) );
		filter1.setAxisQualifierLevels( null );
		filter1.setAxisQualifierValues( null );
		filter1.setTargetLevel( level21 );
		
		CubeFilterDefinition filter2 = new CubeFilterDefinition( new ScriptExpression( "data[\"country_year_total\"] != 120" ) );
		filter2.setAxisQualifierLevels( new ILevelDefinition[]{
			level21
		} );
		filter2.setAxisQualifierValues( new Object[]{
			"2002"
		} );
		filter2.setTargetLevel( level11 );
		CubeFilterDefinition filter3 = new CubeFilterDefinition( new ConditionalExpression( "data[\"country_year_total\"]",
				IConditionalExpression.OP_TOP_PERCENT,
				"50" ) );
		filter3.setAxisQualifierLevels( new ILevelDefinition[]{
			level21
		} );
		filter3.setAxisQualifierValues( new Object[]{
			"2002"
		} );
		filter3.setTargetLevel( level11 );