Add Collabora Online support

[dereks]

Collabora Online is an online document editing and sharing system, similar to Google Docs. It is based on LibreOffice, and has an Open Source license. It is self-hosted (currently it is distributed as a Docker image).

Pydio, which is a web-based file manager similar to RFM, has already added support for Collabora Online. A video of it can be seen here:

https://www.youtube.com/watch?v=OjHtgnL_L7Y

As a wishlist item, it would be nice if RFM could support this too, using a plugin.

Note that Collabora Online is a very large (hundreds of megs) server-side deployment, so it would be a separate download and install. Also, I think it needs a concept of "Users" with it, which RFM does not have built-in.

I will read up on the Collabora Online API and see if this is a plausible feature for RFM.

[psolom]

Collabora looks amazing and powerful tool! It would be great to implement it as a plugin. Thanks for sharing and interest in it.