Add missing license header
Save source exception in CorruptBlockException

ninja patch by Pavel Yaskevich; ninja reviewed by Aleksey Yeschenko
Merge branch 'cassandra-2.0' into cassandra-2.1
Merge branch 'cassandra-2.0' into cassandra-2.1.0
Merge branch 'cassandra-2.1.0' into cassandra-2.1