We strip FQDNs by default because of the inherent problem
of interacting with users, who generally don't like typing
all that extra stuff. However, that creates a problem when
being provided FQDN input during things like nspace registration.

So add an MCA param to control the strip operation instead of
only switching it on/off via info directing during init.
Add logic to the nspace registration process to perform the
strip and add aliases (for the case where the host failed
to provide them).

Signed-off-by: Ralph Castain <rhc@pmix.org>