add possible missing import?

Author: koenpunt

Tests/IGListAdapterTests_IB.m

@@ -17,6 +17,7 @@
 #import "IGListTestAdapterDataSource.h"
 #import "IGListTestCase.h"
 #import "IGTestSupplementarySource.h"
+#import "IGListAdapterInternal.h"
 
 @interface IGListAdapterTests_IB : IGListTestCase
 @end