Example code StreamingBodyParser original at:
https://github.com/mslinn/play21-file-upload-streaming/blob/master/app/services/StreamingBodyParser.scala 
Currently unused.
Implemented assembly of several binary file chunks back to original
single binary file. Basic successful test with test data added.
Added checks and managed corresponding exceptions.
Added deleteChunks utility method.
Added checkUploadComplete helper and corresponding basic test.
Provides reusable functions. First implemented retry as found on the web
plus customised it in a second version providing a extra parameter for
delaying between retries.
Changed checkUploadComplete to throw Exception instead of returning
false. Change putChunksTogether signature.
Adapts to putChunksTogether signature change.
Implemented createElfinAnnexFile method. Creates an empty file at the
expected location given all explicit and implicit information. Returns
its reference to routine writing to it.
Working Api.createElfinAnnexFile() implementation. Creates annex file at
correct location following file chunks uploads.