Request limiting, config improvements

* Added middleware to limit concurrent  request and request body size
* The default configuration now has the defaults

bin/mercureactd

@@ -50,15 +50,12 @@ if (isset($opts['C'])) {
     file_put_contents($file, <<<DEFAULTS
     server:
       address: 0.0.0.0:9000
-      public_url: https://example.com
       websockets: false
       cors:
         allow_origin: '*'
         csp: "default-src * 'self' http: 'unsafe-eval' 'unsafe-inline'; connect-src * 'self'"
       encryption:
         local_cert: ~
-        local_pk: ~
-        passphrase: ~
 
     publish:
       overwrite_ids: false
@@ -78,12 +75,7 @@ if (isset($opts['C'])) {
 if (isset($opts['c'])) {
     $config = Configuration::fromFile($opts['c']);
 } else {
-    $config = Configuration::createDefault()
-        ->setListenAddress('127.0.0.1:8888')
-        ->setAllowOriginHeader("*")
-        ->setContentSecurityPolicyHeader("default-src * 'self' http: 'unsafe-eval' 'unsafe-inline'; connect-src * 'self'")
-        ->setAllowAnonymousSubscribe(true)
-        ->setJwtSecret("!ChangeThisMercureHubJWTSecretKey!");
+    $config = Configuration::createDefault();
 }
 
 $verbose = isset($opts['v']);