publish revocation endpoint, addresses mitreid-connect#520

Author: jricher

openid-connect-server/src/main/java/org/mitre/discovery/web/DiscoveryEndpoint.java

@@ -306,7 +306,8 @@ OPTIONAL. JSON array containing a list of the JWS signing algorithms (alg values
 m.put("op_tos_uri", baseUrl + "about");
 
 m.put("introspection_endpoint", baseUrl + "introspect"); // token introspection endpoint for verifying tokens
-
+m.put("revocation_endpoint", baseUrl + "revoke"); // token revocation endpoint
+
 model.addAttribute("entity", m);
 
 return "jsonEntityView";