[arch-releng] archiso2dual.sh: join both i686 and x86_64 iso in one

This is only just for "start point" and is a DRAFT that works (just setup correct directories and images names). Nothing is stripped, I working on it. Size of iso generated is 782237696 bytes (746MB) http://github.com/djgera/archiso2dual -- Gerardo Exequiel Pozzi ( djgera ) http://www.djgera.com.ar KeyID: 0x1B8C330D Key fingerprint = 0CAA D5D4 CD85 4434 A219 76ED 39AB 221B 1B8C 330D