Add toString() to Any, fix all tests

#KT-4517 Fixed

core/descriptor.loader.java/src/org/jetbrains/jet/lang/resolve/java/lazy/types/LazyJavaType.kt

@@ -49,13 +49,13 @@ abstract class LazyJavaType(storageManager: StorageManager) : AbstractJetType(),
 
     override fun getAnnotations() = Annotations.EMPTY
 
-    override fun toString(): String? {
+    override fun toString(): String {
         if (!_typeConstructor.isComputed()) {
             return "Type constructor is not computed"
         }
         if (!_arguments.isComputed()) {
             return "" + getConstructor() + "<arguments are not computed>"
         }
-        return super<AbstractJetType>.toString()
+        return super<AbstractJetType>.toString()!!
     }
 }