Don't initialize NSS if we don't have to, clean up unused cert refs
Check to see if NSS is initialized before trying to do so again.
If we are temporarily creating a certificate be sure to delete it in order
to remove references to it and avoid NSS shutdown issues.
In the certificate load validator shut down NSS if we end up initializing
it. I'm not entirely sure why but this prevents a later shutdown issue
if we are passed the --ca-cert-file option.