Initial HDFS Readers and Writers implementation.

Basic implementation of a writer and sequential and random readers that operate with streams on HDFS. These operate on Array[Byte] rather than specific kinds of data, so any data being sent in should already be in serialized form.
Why do you ever have to append? Isnt it fine to create new files? We are have to create new files at some not-so-frequent intervals (say 1 minute), because we also need to delete old files, containing data that is not needed any more.