Add test to check volume creation code against upstream encfs

[mrpdaemon]

We need to make sure our volume creation path remains compatible with encfs, with different config options etc. Probably this needs a separate test infrastructure (ie. some scripting to use the encfs command).

[mrpdaemon]

I see that we already have EncFSComparer for this purpose - we just need to add some automated test cases. Maybe a shell script to mount various encfs volume via encfs and then run EncFSComparer on them.

[mrpdaemon]

The other direction also holds true, ie. create volumes with encfs-java and compare them with encfs mounted state.