Fix coala's cache when `--user` is defined

[yukiisbored]

Docker has this weird way of using root as the default user resulting in files which the user can't write to. The only way to fix this is to declare --user=<UID> but this'll cause a problem because there's no home folder so it defaults to /. The workaround for this is to pre-made /.local/share/coala and set the permission to 777 (RWX for everyone)