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.
webui: Improve strings for volume type

"raw" and "local" were really suboptimal, and EqualLogic is a bit better
than EQLX.
Fix keyfile being only defined, when using client cert

Use only client cert, when in use