Google Drive project export declares wrong data type

[tfmorris]

The Export Project to Google Drive command creates a gzip compressed tar archive, but then uploads it to Google Drive without an extension and with a MIME type of application/zip which causes Google Drive to give it a zip extension on download.

OpenRefine/extensions/gdata/src/com/google/refine/extension/gdata/UploadCommand.java

Line 162 in d97d6c6

FileProjectManager.gzipTarToOutputStream(project, fos);

OpenRefine/extensions/gdata/src/com/google/refine/extension/gdata/UploadCommand.java

Line 173 in d97d6c6

FileContent projectContent = new FileContent("application/zip", filePath);

To Reproduce

Steps to reproduce the behavior:

1. Export a project to Google Drive
2. Go to Google Drive and download the resulting file
3. Attempt to unzip the resulting file
4. See error

Archive:  /Users/tfmorris/Downloads/Google Scholar highly cited researchers.zip
  End-of-central-directory signature not found.  Either this file is not
  a zipfile, or it constitutes one disk of a multi-part archive.  In the
  latter case the central directory and zipfile comment will be found on
  the last disk(s) of this archive.

Expected behavior

File is uploaded with the correct type.