Provide a way to import documents and related blobs with nuxeo-csv at the same time

The current nuxeo-csv plugin allows to import documents from a CSV file, but the related blobs have to be available in the ${nuxeo.csv.blobs.folder} folder. To be more user friendly, this PR allows a user to upload a ZIP file containing the CSV file and every related blob.

For example:

• /import.csv
• /folder1/image.jpg
• /folder2/subfolder1/song.mp3

The CSV file can then use "folder1/image.jpg" or "folder2/subfolder1/song.mp3" to add a blob to a document.

Reporter: Florent M
E-mail: florent.munch@sword-group.com