Add a download button when selecting multiple documents

[chdagenais]

We can already edit tags, document type and delete multiple documents.

It would be useful to add a button to batch download multiple selected documents.

Say for example I would like to download all document with house tag, I could select a filtered view according to that, select all, and click download.

[jonaswinkler]

See #211

[chdagenais]

thanks ! sorry I searched if it have been suggested here in discussion, but not in issues

[jonaswinkler]

I know that it's all over the place right now. No worries.