Add missing files - thanks to Mr. Anonymous for reporting them as missing from the 1.8 tarball

cmr=v1.8.1:reviewer=jsquyres:subject=add missing portals4 files
Fix the sequential mapper - it was out-of-sync with the hostfile changes, and we missed the "seq" policy when parsing the --map-by option. Thanks to Bill Chen for reporting it

cmr=v1.8.1:reviewer=jsquyres