Added Demo mode

Demo mode allows to safely run a demo version of the app, with destructive features limited.

Some bugs were also fixed in this commit.

.env.example

@@ -11,6 +11,10 @@ APP_SITEHOMEPAGE=""
 # Void if env is production.
 NONPROD_FORCE_SECURE=false
 
+# Disables certain features for security purposes while running an open authentication system
+# Enable only for demonostration purposes
+DEMO_MODE=false
+
 LOG_CHANNEL=daily
 
 DB_CONNECTION=mysql