Added scripts to build fuseloop with Docker

[timmattison]

Some people had asked for the fuseloop binary but it isn't available on Sourceforge anymore. I quickly built a Dockerfile that rebuilds it on Ubuntu 20.04.

[timmattison]

For issue #2

[jmattsson]

The build issue in #2 is really about the old mountlo utility, which is separate from fuseloop. If you could manage to get mountlo to build in Docker, there are probably quite a few who would be happy.

That aside, I guess there's no harm in adding a Docker file here, even if it seems like overkill for a single-source project.