Allow SAML authentication provider to be named

Using `CMD_SAML_PROVIDERNAME` and the respective auth provider objects
in the configuration structures.

Signed-off-by: Moritz Schlarb <schlarbm@uni-mainz.de>

lib/config/default.js

@@ -144,6 +144,7 @@ module.exports = {
     tlsca: undefined
   },
   saml: {
+    providerName: undefined,
     idpSsoUrl: undefined,
     idpCert: undefined,
     clientCert: undefined,