Importing the testdata gives warnings and import fails

[peetkes]

When I tried importing the testdata. I got an invalid argument warning and the files are not imported into the database:
Warning is:
14/08/18 11:47:59 WARN mapreduce.ContentWriter: Invalid argument (json:INVALIDARG):

[grtjn]

The import doesn't recognize the document type by extension, and falls back to binary, where it should read the JSON documents as text. Solution is to add -document_type text..

[dmcassel]

Thanks grtjn; can you do a pull request?