Allow to auto-generate self-signed SSL certificates

The setup is rather simple. Instead of a full-blown CA, a CSR is
used to create the self-signed certificate.
Make sure PKI certs are there before checking SSL certs

PKI certificates are only generated on non-SUSE platforms, (open)SUSE
provides PKI certs via it's packages. Since by default the SSL certs
will be identical to PKI certs, we can only check for their existance if
they have been generated.
Define conditions for allowing auto-generation of SSL certs.

Only allow to generate SSL certs if all paths to SSL keyfile / certfile
(and ca_certs) are different from the PKI cert paths. If they're the
same, there's no need to auto-generate further self-signed certificates.
Merge pull request #105 from saschpe/release/pebbles/master-ssl-gencerts

https://github.com/crowbar/barclamp-keystone/pull/105

Merged by devtool for cloudsleuth