Additional fixes for keystone SSL support [3/3]

The default for cert_required is wrong (should be false, like upstream).

Also add an attribute to let the user declare that the certificate is insecure; this will be usable from other barclamps if they need to use --insecure options here and there (quantum needs it, for instance).

Crowbar-Pull-ID: 49beb953652e66e14d4600b5509dd9eb9eb2e1cb

Crowbar-Release: pebbles