oracle template: fixes for older releases

oracle template: fixes for older releases

This fixes some issues found by Oracle QA, including several cosmetic
errors seen during container bootup.

The rpm database needs moving on Debian hosts similar to on Ubuntu.

I took Serge's suggestions: Do the yum install in an unshared
mount namespace so the /proc mount done during OL4 install doesn't
pollute the host. No need to blacklist ipv6 modules.

Make the default release 6.3, unless the host is OL, then default
to the same version as the host (same as Ubuntu template does).

Signed-off-by: Dwight Engen <dwight.engen@oracle.com>
Acked-by: Serge E. Hallyn <serge.hallyn@ubuntu.com>