devicePathToName should default to returning a basename.
devicePathToName should default to returning a basename.

This is specifically for the case of DiskFile, which has an
arbitrary file path, but it looks like the entire method could be
replaced with the basename call.

dwlehman/blivet,vojtechtrefny/blivet,dwlehman/blivet,vojtechtrefny/blivet,vpodzime/blivet,AdamWill/blivet,jkonecny12/blivet,vpodzime/blivet,rvykydal/blivet,rvykydal/blivet,jkonecny12/blivet,rhinstaller/blivet,AdamWill/blivet,rhinstaller/blivet