Implemented setup code for the external sort.  No sorting actually happens yet.
Added merge method to merge the buffer full of chunks of size chunkSize with final chunk of size lastChunkSize, outputting into the stream outputStream
Added junit tests for provided data.
Completely reworked to use radix sort and low level IO.
Provided test data, checking sort using checksums of the files.  Converted to JUnit tests
Removed code to empty the buffers between passes, and increased the buffer size.
Added auxiliary git files (readme, license and .gitignore)