create-container: support 32-bit creation on 64-bit OS

Use arch and basearch vars to determine the types
of rpms to install with yum.  Name the local repo download
and create a local yum repo configuration file accordingly.

Add base-i686-container.sh config for creating 32-bit
containers.

Signed-off-by: U. Artie Eoff <ullysses.a.eoff@intel.com>