Fix tapeserver umask to allow directory creation in POSIX filesystems

Fixing issue reported by @ewv: Repack issues seen.

This issue affects FNAL because they are using NFS for their disk file store (which respects the umask) whereas we are unaffected because we use EOS (which inherits the permissions and does not respect the umask).

I will change the umask to 0077 to allow the tape server to create directories with permission rwx------