it works for scala 2.10, but for 2.11 i get:
[ERROR]
/home/koert/src/spark/sql/catalyst/src/main/java/org/apache/spark/sql/execution/UnsafeExternalRowSorter.java:135:
error: <anonymous org.apache.spark.sql.execution.UnsafeExternalRowSorter$1>
is not abstract and does not override abstract method
<B>minBy(Function1<InternalRow,B>,Ordering<B>) in TraversableOnce
[ERROR] return new AbstractScalaRowIterator() {
