Pass -S options to pkgbuild, fix important bugs

- pass all non-recognized -S options to 'pkgbuild create' (uppercased)

- autodetect the directory extracted from the tarball instead of assuming
  it's $PRODUCT-$VERSION

- sanitize EUPS environment by unsetup-ing any setuped packages when before
  setup-ing the dependencies and the package being built

- set up the package being built with -k instead of -j to make it work well
  with 'eups distrib instal -j', where eups doesn't set up the dependencies.