Fix batch-mode handling with changes in e75ad75

The --batch CLI arg now takes no options and enables batch-mode when
present.

init-pki no longer takes a 'force' value which did the same as --batch.

Signed-off-by: Josh Cepek <josh.cepek@usa.net>
Fix incorrect handling of invalid --use-algo option

The prior warn/fallback to rsa didn't work, and fallback is probably the
wrong thing to do, especially for batch callers. It is now an error to
supply an invalid value.

No need to export the EASYRSA_ALGO_PARAMS either.

Signed-off-by: Josh Cepek <josh.cepek@usa.net>