2.0 release candidate (#3808)

* use SAML interface instead of implementation
* moved implementation of SAML configs to system-configuration base class
* bump composer packages
* simplify configuration for different env

config/packages/monolog.yaml

@@ -29,14 +29,6 @@ when@dev:
                 path: "%kernel.logs_dir%/%kernel.environment%.log"
                 level: info
                 channels: ["!event"]
-            # uncomment to get logging in your browser
-            # you may have to allow bigger header sizes in your Web server configuration
-            #firephp:
-            #    type: firephp
-            #    level: info
-            #chromephp:
-            #    type: chromephp
-            #    level: info
             console:
                 type: console
                 process_psr_3_messages: false