sbin/hammer - Remove trailing '/' from paths.

sbin/hammer - Remove trailing '/' from paths.

  When operating PFSes through symbolic links, it was not
  possible to specify the trailing backslash since that
  translated to the PFS root dir instead of the symbolic link
  to the PFS itself. This caused problems when upgrading or
  downgrading PFSes (and probably in other cases too).
  The error was "Directory not empty".

  This commit should solve those cases, but keep in mind
  there are other cases where it is actually not possible
  to complete certain operations (like while destroying
  PFSes).

Reported-by: Siju George, others